Meatball Sliders From The Little Owl In New York - cooking recipe

Ingredients

1/2 lb ground beef
1/2 lb ground pork
1/2 lb ground veal
1/2 cup panko breadcrumbs
1/2 cup water
8 tablespoons pecorino romano cheese, divided (freshly grated)
1 large egg
1 large egg yolk
1/4 cup plus 2 tablespoons fresh parsley, chopped
1 teaspoon salt
1/2 teaspoon ground black pepper
1/4 cup vegetable oil
2 tablespoons olive oil
1 cup chopped onion
6 garlic cloves, chopped
1/4 cup fresh basil leaf, packed
1 1/2 teaspoons fennel seeds
28 ounces whole canned tomatoes
14 1/2 ounces whole canned tomatoes
arugula leaf (optional)
18 small soft rolls, split horizontally

Preparation

Mix all meats, panko, 1/2 cup water, 6 tablespoons cheese, egg, egg yolk, 1/4 cup parsley, 1 teaspoon salt and 1/2 teaspoon black pepper in a large bowl. Form into 18 2-inch meatballs.
Heat vegetable oil in large skillet over medium-high heat. Working in batches, fry meatballs until brown all over. transfer to plate. Reduce heat to medium. Add olive oil to skillet. Add onion, garlic, basil and fennel seeds. Saute until onion begins to brown, about 5 minutes. Add all tomatoes with juices. bring to a boil, scraping up browned bits. reduce heat to low, cover with lid slightly ajar, and simmer, stirring occasionally, about 30 minutes.
Puree sauce in processor until almost smooth. Return to same skillet. Add meatballs. Cover with lid slightly ajar and simmer until meatballs are cooked through, stirring occasionally, about 30 minutes longer.
DO AHEAD: can be made 1 day ahead. Cover; chill.
Place arugula leaves on bottom of each roll, if desired. Top each with 1 meatball. Drizzle meatballs with some of sauce and sprinkle with remaining 2 tablespoons parsley and 2 tablespoons cheese. cover with tops of rolls.