For the Meatloaf
Preheat the oven to 425°F (220°C).
In a large mixing bowl, thoroughly combine the ground beef and lamb. In a separate bowl, beat the eggs, then mix in the milk and oats. Pour this mixture over the meat and stir until well combined.
Add the parsley, onion, green pepper, lemon juice, orange zest, pine nuts, raisins, allspice, thyme, salt, pepper, garlic, and Worcestershire sauce to the meat mixture. Mix gently but thoroughly to ensure even distribution of ingredients.
Shape the mixture into a firm, oval loaf and place it in a roasting pan. Drizzle the surface with melted butter. Bake for approximately 1 hour, or until the meatloaf is cooked through. Serve alongside the prepared sauce.
For the Sauce
Melt the butter in a skillet over medium heat. Add the onion, green bell pepper, and bay leaf, sautéing until the onion softens and becomes translucent, approximately 5–10 minutes.
Incorporate the garlic, lemon juice, raisins, thyme, allspice, and canned tomatoes. Gently break the tomatoes into smaller pieces as they cook. Simmer the mixture for about 30 minutes, allowing it to thicken slightly.
Stir in the tomato paste and cook for an additional 15 minutes, ensuring the flavors meld together. Remove from heat, add the parsley, and mix well. Serve the sauce warm over slices of the meatloaf.