1) To make the tomato sauce:Pure tomatoes with their juice in a blender and transfer to a bowl.

2) Heat oil in a large heavy pot over medium-high heat and saut onion until golden, about 6 minutes.

3) Add garlic and saut, stirring, 1 minute.

4) Add tomato pure, sugar, bay leaf, and 1 1/2 teaspoons salt and simmer, uncovered, stirring occasionally, until thickened, 40 to 50 minutes. Discard bay leaf.Make meatballs while sauce simmers:Stir together bread crumbs and milk in a large bowl and let stand 10 minutes.

5) Add meat, garlic, cheese, eggs, parsley, oregano, marjoram, 1/2 teaspoon salt, and 1/2 teaspoon pepper and blend until just combined well (do not overmix). Form level 1/4-cup portions into meatballs.

6) Heat oil in a 10-inch heavy skillet over medium-high heat hot and fry meatballs, about 6 at a time, turning occasionally, until well browned and cooked through, 4 to 6 minutes per batch.

Transfer to paper towels with a slotted spoon.Simmer meatballs in sauce and assemble sliders

1) Add drained meatballs to tomato sauce and simmer, stirring occasionally, until meatballs are heated through.Assemble sliders with a meatball and 1 tablespoon sauce per bun.

2) Garnish with baby greens and secure each with a wooden pick.