Boil, steam, grill or broil the eggplants until soft but not mushy. Peel off the skins, leaving the stems on. With the back of a fork, flatten the meat of the eggplants.
Beat the eggs and flour lightly and season with salt and pepper. Stir in the sisig, chopped onions and garlic. Divide the egg-sisig mixture into as many eggplants you prepared. Place the mixture on the flattened eggplants, patting the meat to make sure it is compact.
Heat about 3 tbsps. of cooking oil in a non-stick frying pan (you will need more is using an ordinary pan). Carefully slide one stuffed eggplant onto the hot oil. Cook over medium-high heat, about 5-7 minutes or until golden brown then flip to brown the topside.
Repeat until all the sisig-stuffed eggplants are cooked.