Preheat the oven to 220°C. Cut off the top of the peppers and core them. Peel and slice the onions.
Cook the rice in a pan of boiling salted water according to the cooking time indicated on the packet. Drain and set aside.
Melt the onions and garlic in a pan with 2 tablespoons of oil. Simmer on low heat for about 8 minutes.
Mix the meat, rice, onions and garlic in a bowl. Season with salt and pepper.
Top the hollowed-out peppers with the mixture and place them in an ovenproof dish, adding a little water to the bottom of the dish. Bake for 35 minutes. Serve immediately.