This is frequently served at special occasions in Chinese restaurants. Presented as an appetizer, it will serve 6.
USING A THIN CLEAVER, cut away the wings and thigh joints and pull off the skin, cutting it where necessary. Set the skin aside. Bone the breasts. Scrape all the meat you can from the bone. Neatness does not count! To remove the leg meat, make a slit the length of the leg to the bone. Pull the meat away, cutting it off the bone where necessary. Remove the small but tough tendon from each leg. Bone the second squab, then add the bones, feet, heads and wings to 1 cup chicken broth and reduce the liquid to 1/2 cup. With 2 cleavers, start chopping the meat, until finely minced. Set aside.
Thinly slice the squab skin. Stir-fry the skin in a little oil to render the fat and crisp the skin. This takes about 10 minutes. As the skin browns, move it up the side of the wok. Set the crisped skin aside.
The preceding steps can be done up to 8 hours in advance. Keep the minced squab refrigerated if it must stand longer than 1 hour. Stir-fry the squab in the oil with the garlic over high heat until is is browned lightly. Add the remaining minced ingredients, mix them well and add the reduced chicken broth, sugar, soy sauce, rice wine or sherry and oyster sauce. Bring the mixture to a boil and stir in the cornstarch dissolved in broth. Stir in the crisped skin and transfer the mixture to a serving plate.
Serve the dish surrounded by lettuce cups. Each diner wraps some of the squab mixture in a lettuce cup.