Chef John's Italian Meatballs

Name: Chef John's Italian Meatballs
Prep time: 20 min
Cook time: 35 min
Total time: 55 min
Cuisine: Italian
Ingredients: 0.33333334326744 cup plain bread crumbs; 0.5 cup milk; 2 tablespoons olive oil; 1 onion, diced; 1 pound ground beef; 1 pound ground pork; 2 eggs; 2 tablespoons grated Parmesan cheese; 0.25 bunch fresh parsley, chopped; 3 cloves garlic, crushed; 2 teaspoons salt; 1 teaspoon ground black pepper; 1 teaspoon dried Italian herb seasoning; 0.5 teaspoon red pepper flakes