In a large pot, over medium heat, sweat onion, then add garlic and tomato. Cook for 5 minutes. Add sugar, vinegar and remaining ingredients and cook down for 45 minutes. Remove the bay leaf and run through a food mill. Set aside.
Dice the meat and mix with salt. Grind twice with 1/4-inch die. Add all other ingredients except egg and paddle in standing mixer for 1 minute. Add the egg and mix to combine.
Form into 1-inch round balls, dust with all-purpose flour. Add a coating of oil to a large skillet, and shallow-fry the meatballs until golden. Cover with tomato sauce and simmer for 10 minutes over low heat. Sprinkle with ricotta and chopped cucumber and serve.