1.5 liters Fish stock or vegetable stock
125 g Raw shrimps
1 Small shallots, finely chopped
2 tablespoons Nuoc cham sauce
1/4 Pepper
Few pieces Leaves from 1 bunch of watercress

Pour the stock into a large saucepan and gently bring to the boil. Peel the shrimps, de-vein them and set aside the shells. Pound the shallots in a mortar. Add the shrimps, nuoc cham sauce and pepper. Pound again to ensure the shrimps absorb the other flavors. When the stock is boiling, add the shrimp shells and simmer for 5 minutes. Remove and discard the shells, then add the shrimp mixture. After about 1 minute, when the shrimps have changed color, add the watercress. Simmer for 1 more minute and serve.