First make the dressing by pounding the salt and garlic with a pestle and mortar until it looks creamed. Add oil, vinegar, sesame seeds, soy sauce, toasted chili powder, and dark soy sauce. Whisk for a few seconds with a fork to combine.
Cut half of the tofu into 1 centimetre thick (ish) triangles. Slice the other half into thin squares. The shape doesn’t actually matter, but the more surface area there is, the more room there is for the dressing to coat. With this in mind, try to avoid massive cubes.
Heat two inches (5 cm) of vegetable or peanut oil in a wok or saucepan to medium high heat. The oil should have a temperature of around 185 degrees Celsius or (365 degrees fahrenheit), so if you have a thermometre then use it. If not, the oil is ready when you add a piece of tofu and it begins to sizzle almost immediately after you add it to the fat.
Deep fry the tofu in batches, ensuring the pan is never overcrowded and the pieces have room to float freely without overlapping. Fry for about 5 minutes, until they are golden. You should see visibly crispy edges. Remove from the oil with a mesh skimmer and leave to drain on a plate lined with kitchen roll.
Add the unfried tofu and dressing to a large bowl and stir gently to coat. Quickly toss the fried tofu through and top onto a plate to serve. Garnish with herbs, lime leaf, fried shallots, and peanuts, if using. Serve immediately.