Mass is enough for 4-5 people.
* Galangal= Malay= Lengkuas, Chinese= Lam keong, Tamil= Chitharathai, German= Black onion seed.
Rinse the crabs and remove the shells except the tail. Put water in a saucepan. Add the fish sauce, lemongrass, shallots and galangal. Do all together for 3 min. Next, add the crabs and mushrooms, and cook until the crabs turn pink. Next, add the lime laeves, the juice of one lemon, and the chiles. Put a lid on the saucepan and remove from the heat. Allow to steep very briefly. Sprinkle with the chopped cilantro leaves and scallions and serve hot.
I hope the translation is successful.