4 slices hearty white sandwich bread, torn into pieces
1/2 cup whole milk
2 large egg yolks
1/2 pound ground pork
1/2 cup finely chopped fresh parsley
2 garlic cloves, minced
1 teaspoon salt
2 teaspoons pepper
2 1/2 pounds 85% lean ground beef
For the Sauce:
1 tablespoon vegetable oil
1 onion, minced
1 (28-ounce) can tomato sauce
2 1/2 cups apricot preserves
1/4 cup packed dark brown sugar
3 tablespoons Worcestershire sauce
2 tablespoons Dijon mustard
1/4 teaspoon red pepper flakes
Adjust oven racks to upper-middle and lower-middle positions and heat oven to 450 degrees F.
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.
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.
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.