1In a large bowl, mix together ground beef, grated onion, grated garlic (2 cloves), bread crumbs, egg, black pepper, paprika, red pepper flakes, cumin, 1 teaspoon salt, and 0.5 cup water until well combined.
2If possible, let the mixture rest in the refrigerator for 1 hour. Otherwise, proceed to shape the meatballs.
3Shape the mixture into meatballs.
4Slice the potatoes, green peppers, and tomatoes lengthwise.
5Arrange the meatballs and vegetables alternately in a baking tray.
6For the sauce, melt butter in a pan and sauté tomato paste. Add grated garlic (1 clove) and sauté briefly.
7Add 1 teaspoon salt and 2 cups water, mix well, and pour the sauce evenly over the meatballs and vegetables.
8Cover the dish with moistened and squeezed baking paper.
9Bake in a preheated oven at 190°C (375°F) until cooked through.
10Near the end of baking, remove the baking paper and bake a little longer until the top is golden brown.