Squeeze out the excess water by weighing down the bean curd with a cutting board or flat platter for about 2 hours. If you are in a hurry, boil the bean curd in salt water (6 cups water, 1 teaspoon salt) for 2 minutes. Drain. Cut each piece criss-crossly, making 16 triangle pieces.
Mix the chopped pork, fish, shrimp, and onion with marinade. If too dry add 2 or