It’s true what they say about an idea being impossible to kill. I’ve learned this in trying to convince friends that pressing tofu is a Western concept, perhaps even a mistreatment. The idea of boiling tofu in salted water, like they do in China and other East Asian countries, must be fiction, some culinary oddity I’ve made up. They’re so unconvinced they don’t even ask me to explain.
And so I’ll explain the practice and its logic here instead. First I'll talk about the process of pressing tofu before moving onto an explanation of why boiling is both more effective and efficient.
Before we press on (ha ha ha), however, I want to make clear this guide does not refer to silken or super soft tofu. Always assume I am referencing firm-ish bean curd throughout.
My first encounter with boiled tofu as a preparation method
The first time I encountered the idea of boiling tofu was somewhere between 2011-2012, as an observer in a restaurant kitchen in Thailand. As my esurient eyes scanned the kitchen, hungry to understand the various bottles and jars, they landed on the simplest of things: a pot filled with cubed tofu and water.
Language constraints prevented further inquiry so I took to my own research, but I struggled to find much at all. Not one Western cookbook in my collection or on bookshop shelves discussed tofu preparation beyond pressing (to this day this still stands mostly true). It wasn’t until I came across Andrea Nguyen’s then just published book Asian Tofu (highly recommended) before I found an in-road to some answers.
Additional research, combined with compounded experience over time, answered many of my questions and informs how I prepare and cook tofu today. I hope what I’ve learned will be helpful for you as well.
Why do people press tofu?
The purpose of both boiling and pressing tofu is to reduce moisture. The former process is grounded in both reason and preservation of the tender quality of bean curd, while Western cooking educators are hellbent on the view that tofu is unmanageable without the firmest, chewiest possible texture. Cookbook authors instruct readers to use weighty objects or specialist devices to aid in squeezing water out of bean curd in order to achieve this, to make less firm tofu into more firm tofu.
The reason why you can, for the most part, buy tofu made into so many different levels of firmness and consistency is so you take home the right tofu for the job without need for further processing. Western cookbooks and education materials often prime us to focus on the firmest of textures possible, so little attention is paid to other varieties. On top of this, the types of tofu you can buy at Western supermarkets is more limited. This might be a reason why Western consumers may not realise such a variety of bean curd exists to begin with.
Should you press tofu?
In my day to day cooking I face two scenarios that call for pressing tofu.
In Thailand the type of tofu used for some dishes (e.g. pad thai) is a solid, super compressed block of bean curd with no excess water. This isn’t easily found in UK supermarkets (nor in US shops, so far as I’ve seen). When I want to cook recipes that call for such dense bean curd then I press tofu, only because I am unable to purchase it. Most recipes, however, don't require this level of firmness.
My subsequent reason for pressing tofu is if I’m making something that requires ground up or blended tofu as an ingredient (e.g. mock meats), and I want to minimise liquid.
To summarise, I don’t look at boiling as an alternative to pressing so much as I see them as two wholly different treatments. 99% of the time boiling is the better (and quicker) option. Pressing tofu is rarely necessary. Read on for further explanation of why my claim is true.
Boiling tofu for texture and firmness
In Asian Tofu, Nguyen notes it’s common practice in Chinese cooking to blanch tofu prior to use in preparations that require simmering. This step gives structural integrity to the tofu to see it through intensive boiling processes without breaking apart during cooking (e.g. stews). This same logic applies for any cooking method that would see your tofu knocked about a bit.
The act of adding tofu to salted hot water for a time and then removing it to drain and dry firms up the texture. The process counterintuitively draws moisture from the outer layers because heat brings some of the innermost liquid to the surface of the curd, which you can either blot off with kitchen roll (or a tea towel) or leave to steam dry. Furthermore, the use of salt adds seasoning that improves the flavour.
After draining the salt water treated tofu, the surface firms up. Of particular importance if you intend to fry the tofu is ensuring the surface is dry, which occurs naturally if you leave the hot strained tofu on a tea towel to dry out.
This method is the secret to restaurant quality crispy fried tofu
Wetness in any form is not conducive to crispiness because crispiness is a byproduct of dehydration. So now you have this lovely salt treated tofu with a dry surface. That lack of moisture is going to help you achieve a nice browned crust because you’re not battling a bunch of water. Additionally, the dry exterior means you won’t be dealing with hot oil splashing around your kitchen (and hands and face).
Is this beginning to make sense? I’ll (try to) explain with a further example of frying tempura for added clarity.
It’s all to do with water content
Have you ever made (or ordered) tempura that went limp too quickly after it was cooked? This has to do with water, which most foods contain in high quantities. What happens to water when you heat it? It boils and steam is produced.
As we’ve already established, moisture is the enemy of crispiness.
When you batter and fry your ingredient, you’ll see little bubbles fizzing around the food when it’s in the hot oil. This is the water escaping (both from the ingredient you’ve battered and from the batter itself). When food is heated, the water inside heats up, gets steamy, and pushes its way to the surface. This outward motion not only allows the release of water, but also prevents oil from seeping into the food (to a certain point, but that’s for another discussion). When done well, you end up with a piece of food cooked in the middle and crispy on the outside.
Apply this example to tofu and two things become more clear.
First, the mechanism by which water inside of food can travel to the surface when it’s heated is illustrated more plainly. When food is fried in oil, you can physically see the water escaping as it rises to the surface of the food. The same process of drawing inner moisture to the surface happens when you boil tofu (it’s just not visible to the naked eye).
Second, the reason why removing as much moisture as possible is key to ensuring a more crispy outer layer also becomes more apparent. Because excess moisture is removed from the outer layers of the tofu in boiling, the frying process is more effective. In other words, the crispy texture bestowed from frying is due to dehydration of the surface layers of the tofu, which you’ve aided by the boiling process beforehand.
Marinating tofu is a con. Heat is the answer.
Another myth I wish cookbook authors and bloggers would put to rest is that of the efficacy of marinating tofu. If you don’t believe me, try it for yourself. The next time you plop a slab of tofu into your overnight marinade, slice it the next day and see for yourself how little that liquid has penetrated the bean curd.
Tofu is a pretty dense substance, and marinating works with foods that are more porous in structure. The surface of many of the high protein foods we’re told to marinate are barely permeated when we do this. Again, this is a Western approach to treating tofu that I’ve yet to see elsewhere.
You might argue this is untrue based on the well executed end result of a recipe you’ve followed. Let’s say you’ve followed all the instructions for a marinated and then baked tofu recipe. The flavours of the marinade have penetrated the protein evenly and adequately, so you might argue the act of resting the tofu overnight in seasoned liquid did its job.
Ah, but it didn’t. The reason the tofu is replete with seasoning to its centre is because you cooked it in the marinade. Just like tofu boiled in salted water tastes lightly brined, cooking tofu in soup, sauce, or marinade is what drives the curd to take on flavour. As Hannah Che succinctly states in her brilliant book The Vegan Chinese Kitchen, "Tofu absorbs flavo[u]r when it’s hot, not when it’s cold."
For reference, check out the tofu photo I above. This is the black tofu from the photo I posted toward the beginning of this post, sliced in half. The method of preparing this type of tofu (black tofu, or tao hoo dam เต้าหู้ดำ) is to simmer it slowly for a long time (days, in this case). See how the cooking liquid has permeated the entire block? You would never achieve this with a cold marinade.
There are some exceptions to the rule that marinating is a con, but these only apply to tofu that has been processed beyond a fresh block. Tofu that has been frozen and defrosted undergoes a structural change to the extent that the block will take on liquid in a way that untreat tofu will not. Similarly, other treated tofu products (e.g. bean curd puffs) will absorb liquid more readily.
Methods of treating tofu with boiling water
I use a 2% salt solution, so for 1 litre (1,000 millilitres) of water I add 20 grams of salt (1000 x .02 = 20).
There are two methods for treatment.
- Bring the salted water to the boil in a saucepan. Add the tofu and simmer.
- Add the tofu and salt to a bowl. Boil the kettle and pour the water over the tofu.
I also like to add some MSG for additional seasoning.
How long to boil tofu in salt water
If you're boiling the tofu on the hob, 5-10 minutes will suffice. The longer you simmer, the more seasoned your tofu will be.
If you're pouring boiling water over tofu, without an additional heat source, leave it for 15-20 minutes.
Do I have to use salted water for boiling tofu?
If you're planning to use your tofu in a braised dish or stew with a longer cooking time, use unsalted boiling water. The tofu will pick up the seasonings of the liquid as you continue to cook it, rendering the salt unnecessary.
Boiled tofu for seasoning and texture (as an alternative to pressing)
- 750 millilitres water
- 1 tablespoon salt
- ½ teaspoon MSG optional, but recommended
- firm tofu, cut into cubes or slabs depending on what you're cooking
- Add the water, salt, and MSG to a medium saucepan and bring to a rolling boil. Tip the tofu in, knock the heat down to a low simmer, and cook for 10-15 minutes.
- Alternatively, add the salt, MSG and tofu to a heatproof bowl and pour the boiling water on top. Leave for 15-20 minutes.
- Strain the water away from the tofu and lay the tofu pieces on a tea towel or kitchen roll (with space in between each piece). You can either blot the moisture off the surface of the pieces or leave them for 20-30 minutes to steam dry. Don't leave the tofu pieces to dry in a colander or they will begin to stick together.