Clean the squids. Holding the tentacles, pull out the head. Cut off the intestines and the eyes. Remove the backbone. Pull off the skin (see illustrated instructions). Wash the cavity under running water. Sprinkle inside and with salt and pepper.
Finely chop trimmed squid heads, bell pepper, onion and tomatoes. Mix with garlic. Season with salt and pepper.
Stuff each squid with the chopped vegetables mixture. Push the mixture inside the cavity with your finger. Secure the opening with a toothpick.
Grill squids about 6 inches above live coals (f you place them lower, the outside might be burned before the inside in fully cooked), about 4 to 5 minutes on each side. The best way to do it is to roll the squids while cooking to make sure that they are evenly cooked.
Remove toothpicks before serving the grilled stuffed squids.