This recipe and others can be found in the following article:
3 live mud crabs, about 1 pound each
2 purple onions
1 (1-inch piece) of ginger root, peeled
2 cloves garlic, chopped
2 to 3 red chiles (or to taste)
4 tablespoons vegetable oil
2 ripe tomatoes, chopped
1 heaped tablespoon taucheow (brown soybean paste)
1 tablespoon sugar
Light soy sauce, if desired
Subdue the crabs by storing them for an hour or so in the freezer.
Bring to a boil a pot of water large enough to submerge crabs. Boil the crabs for about 5 minutes or until they turn pink. Remove with tongs and plunge into cold water to stop the cooking process.
Cut away the strings or rubber bands from the claws and pull off the shells by prying under the underbelly flaps. Remove the head sacs, found within the shells, and the spongy gills. Using a knife, detach claws and cut the bodies into 4 or more parts. Use a pestle to crack claws. Leave aside.
Make the sauce. Put the onions, ginger, garlic and chile in a food processor and pulse until it comes into a thick paste.
Heat the oil in a wok. When it's hot, sautee mixture till fragrant, then add tomatoes. Cook until the mixture is caramelized, then add the taucheow and sugar. Stir well and allow to simmer, adding a little water if it seems too thick, till the flavors come together.
Add the crab pieces to the wok and toss to coat. Taste, and season with a drizzle of light soy sauce, if needed. Top with chopped Chinese celery and serve immediately with crusty bread on the side.