Preheat Oven: Set your oven to 350°F (175°C). This temperature is perfect for baking the meatloaf to a juicy perfection.

Combine Ingredients: In a large bowl, mix ground beef, salt, black pepper, chopped onion, chopped bell pepper, beaten egg, diced tomatoes, oats, ketchup, brown sugar, and mustard. Stir gently until everything is well combined, making sure not to over-mix for a tender loaf.

Shape Loaf: With clean hands, shape the meat mixture into a loaf. Place it in a baking dish, ensuring it’s compact but not overly packed, which helps it cook evenly.

Bake Meatloaf: Slide the baking dish into the preheated oven and bake for 1 hour. You’ll know it’s ready when the meatloaf is cooked through, with juices running clear and a golden crust on top.

Rest Before Slicing: Once done, take the meatloaf out of the oven and let it rest for about 10 minutes before slicing. This will help the juices redistribute, keeping every slice moist and flavorful.

Optional: Serve with a drizzle of extra ketchup on top for added flavor.