Step 1

Adjust oven racks to upper-middle and lower-middle positions and heat oven to 450 degrees F.

Step 2

In large bowl mash bread, milk, and egg yolks with a fork until smooth. Add pork, parsley, garlic, salt, and pepper and mix until combined. Add beef and mix until combined.

Step 3

Using a tablespoon, roll meat mixture into 1¼-inch meatballs and place on a rimmed baking sheet. Bake meatballs on 2 rimmed baking sheets until cooked through and beginning to brown, 12 to 15 minutes, switching and rotating sheets halfway through cooking.

Step 4

While the meatballs are baking, heat oil in Dutch oven over medium-high heat until shimmering. Cook onion until softened, about 5 minutes. Mix in tomato sauce, preserves, sugar, Worcestershire, mustard, and pepper flakes and bring to boil. Reduce heat to medium-low and simmer until sauce is thickened, about 15 minutes. Add meatballs and simmer until 5-10 minutes.