In a large bowl, combine the ground beef, grated onion, grated garlic, breadcrumbs, sparkling water, parsley, black pepper, paprika, red pepper flakes, cumin, and salt. Knead until well mixed, then shape into meatballs slightly larger than a walnut.
Slice the onions and peppers into thin strips and spread them in a baking dish. Add the garlic cloves, olive oil, oregano, red pepper flakes, and salt, tossing until evenly coated.
Arrange the meatballs on top of the vegetables.
Whisk together the tomato paste, red pepper paste, hot water, and salt. Pour evenly over the meatballs and vegetables.
Wet a sheet of parchment paper, squeeze out excess water, and use it to cover the baking dish.
Bake in a preheated oven at 180°C (350°F) for about 35-40 minutes, until the meatballs are cooked through and the vegetables are tender.
Remove the parchment paper, sprinkle generously with grated cheese, and return to the oven for a few more minutes until melted and golden.
Notes
Serve hot with crusty bread or steamed rice to soak up the sauce. Leftovers keep in the fridge for up to 3 days.
Keyword Baked meatballs in the oven, One-pan meatballs and vegetables, oven-baked meatballs with vegetables