Soak toast in cold water. Peel 1 onion and chop very finely. Knead minced meat, diced onion, 1 1/2 tsp salt, 1 tsp pepper, eggs and squeezed bread. Form approx. 24 balls (approx. 4 cm Ø) from the minced mass with wet hands.
Heat 2-3 tablespoons of olive oil in a large frying pan, fry meatballs for about 8 minutes over medium heat, turning them over and taking them out. Meanwhile peel 2 onions and garlic and chop finely. Wash, clean and chop the tomatoes.
Heat 2-3 tablespoons of olive oil in a saucepan, sauté onions and garlic in it, add tomato paste, sauté briefly and add tomatoes. Season with salt, pepper and paprika. Bring to the boil and simmer at medium heat for 10-12 minutes.
Season again with salt, pepper, paprika and sherry. Add meatballs, heat briefly. Arrange in small bowls garnished with basil leaves.