In a bowl combine the veal, egg, bread crumbs, parsley, and pecorino and season with salt and pepper. Shape lightly into 1-inch balls (about 36).

Heat 2 tablespoons of the oil in a frying pan. Cook the veal balls over medium heat until brown all over and just cooked through, about 12 minutes. Transfer to a plate lined with paper towels to drain.

Add the remaining 2 tablespoons of oil to the pan and stir in the onions. Season with salt and cook over medium-low heat until the onions are limp, about 15 minutes, stirring often. Don’t let the onions brown.

Stir in the vinegar, sugar, and water.

Return the meatballs to the pan and gently turn to coat them lightly in the sauce. Cover and cook over medium-low heat for 5 minutes, shaking the pan frequently. Transfer to a serving dish and cool. Serve at room temperature.