- 1.5 kg rice-field crabs (medium-sized, purple-colored ones), soaked in the rice-washing water for 2 hours to remove the mud, and re-wash the crabs with clean water. Remove the apron (V-shaped piece on the bottom) and the top shell away. Take the soft, orange crab-roe inside the shell, add some pepper, and set aside.
- Grind or pound the crabs well with a teaspoon sea salts, then add about 3 liters water and sieve the mixture to obtain the liquid part of this mixture only. Repeat this step several times to get as much crabmeat in the liquid as possible.
- 500 g clean, ripe tomatoes, cut into 6 pieces. Stir-fry a half of tablespoon shallots and 2 tablespoons vegetable oil with the tomatoes.
- 100 g ripe tamarind pulp (only use the flesh of tamarind) or dracontomelum bruised and cooked with a quarter liter of water. Sieve the mixture to obtain the juice.
- Heat about 3 tablespoons vegetable oil, add the crab-roe, annatto seed oil, and some sea salt; and then stir-fry.
- Pour the liquid part of pounded crab into a stockpot, add 1 tablespoon fine shrimp paste and simmer the mixture so that the mixture becomes hot gradually (vigorous heat will make the scum of pounded crabmeats not to be clotted into lumps). After the crabmeats have clotted into the lumps and the broth becomes clear, pour the mixture of the fried tomatoes and the crab-roe into the stockpot. Some tamarind juice, salts or fine shrimp paste may be added. Keep on simmering the broth.
- Herbs: Splitted water spinach (Ipomoea aquatica), Vietnamese green perilla (Elsholtzia ciliata), thinly-sliced banana blossom, some aromatic herbs.
- Pure fish sauce, lime, chilies, fine shrimp paste.