If using dried mushrooms, soak the mushrooms in warm water for about 30 minutes or according to package directions. Remove from liquid and strain liquid well. Set aside the liquid to use later. Drain and rinse the mushrooms.
In a medium sized bowl combine the ground beef, pork, half of the onions, parsley, garlic, and the salt and pepper to taste. Form the mixture into 1-inch balls and roll in the flour.
Heat the 1/4 cup oil in a large heavy pot and brown the meatballs in batches. Remove from the pan and keep warm in the oven. Alternatively, you can bake the meatballs (not rolled in flour) at 375 for about 15 to 20 minutes.
When all the meatballs are cooked, prepare the sauce. Add the remaining tablespoon oil to the drippings in the pot. Add the remaining onions and the fresh mushrooms if using, and sauté until they become translucent. Add both cans of tomatoes and the reserved mushroom liquid and the porcinis if using those. Stir together over medium heat. Add the meatballs and cook over low heat for about 20 minutes. Stir in the olives and heat through.
Serve the meatballs and sauce over hot cooked potatoes.
To freeze: Divide the meatballs and sauce into meal-sized portions in plastic containers with lids. Chill completely before freezing. To serve from frozen: Defrost and heat completely.
Nutritional values are approximate and are based on 1/8 of the recipe. Refrigerate leftovers promptly and use within 4 days.