Cut the tofu into bite-sized pieces and fry in a pan until golden. Wash the tomatoes and cut into wedges. Trim the roots off the straw mushrooms, wash, soak in lightly salted water, then drain. Pick and wash all the herbs, then soak in lightly salted water.

Wash the pork fat, drain, and cut into large pieces. Place the pork fat in a pan and cook until it renders and becomes crispy. Remove the crispy pork fat and set aside.

Clean the field crabs by tossing with a little salt and rinsing well. Remove the shells and collect the crab roe. Pound or blend the remaining crab meat. For a richer broth, add a pinch of salt while pounding, then strain the crab mixture with water 2-3 times to get enough crab liquid. Add 1 tablespoon seasoning powder, stir gently, and cook over medium heat until the crab forms curds. Remove the crab curds and set aside. (You can also leave the crab curds in the pot if you prefer.)

Heat a pan and sauté chopped shallots until golden. Add the crab roe, stir quickly, then turn off the heat and transfer to a bowl. Next, briefly sauté the tomatoes and straw mushrooms. For a richer color, you can add 1 tablespoon annatto oil. After sautéing, add the tomatoes and mushrooms to the crab broth, along with a bit of tamarind water, a little shrimp paste, and season to taste. Simmer on low heat, then add the fried tofu.

Add chopped scallions and cilantro to the pot, adjust seasoning to taste, then turn off the heat.

To serve, place rice vermicelli noodles in a bowl, ladle over the broth with tomatoes, mushrooms, tofu, crab curds, and crispy pork fat. Serve with fresh herbs and shrimp paste on the side.