Heat a large-ish saucepan to medium high heat and add the chickpea flour, stirring constantly for about 5 minutes until it turns a uniform toasted light brown. Shake it into a separate bowl, rinse the pot, and put back on the heat to make the stock.
Add the oil to the saucepan, along with the onion. Fry until crispy and brown, stirring often. Add the garlic and turmeric and fry for another minute. Tip in the water and the dried shiitakes, kombu, soy sauce, salt, ginger, Persian limes, and makrut lime leaves. Knock the heat down to medium low, and leave to simmer for 30-35 minutes. Drop in your halved cherry tomatoes.
Remove kombu. Ditto mushrooms and set aside to cool.
Whisk the toasted chickpea flour into the coconut milk until there are no lumps and then pour the slurry into the simmering stock. Stir constantly until the soup thickens and leave to simmer for another 5 minutes. Have a slurp of the liquid and add more salt and/or pepper to taste.
Grab and bowl and lump your precooked noodles of choice in the bottom. Pick out the lime leaves, dried lime, and ginger slices from the broth and pour the remaining liquid over the noodles. Slice up those shiitake mushrooms and add them to your bowl, along with the blanched greens. Squeeze fresh lime juice over the lot and top with any combination of the optional condiments listed.