Heat 1/4 cup olive oil in a large pot over medium heat. Add onions and cook until translucent. Add pureed tomatoes and tomato sauce, along with red pepper flakes and bay leaves. Season lightly with salt and pepper. Bring to a simmer and cook on low, covered, for 30 minutes. Meanwhile, make meatballs.
In a large mixing bowl, combine pork, beef, panko, Parmesan cheese, parsley, garlic, eggs, salt and pepper. Mix well to combine.
Form meatballs. (I use food-safe gloves to mix everything together and form the meatballs). Lightly coat meatballs with flour.
Heat 1/4 cup olive oil and 1/4 cup vegetable oil in a large skillet. Place meatballs in pan, making sure meatballs do not touch each other. Brown on all sides.
Drain meatballs and add to tomato sauce. Cook meatballs in sauce for 30 minutes, stirring occasionally. Add 1/4-1/2 cup water if necessary to loosen up sauce.
Adapted from Lidia's Italian-American Kitchen by Lidia Matticchio Bastianich
. To make this recipe gluten-free, use gluten-free panko breadcrumbs and cornstarch to coat the meatballs.