Preheat your oven to 350°F.

Cut the bell peppers in half lengthwise and remove stems and seeds. Place them cut-side up on a greased baking sheet. Cover with foil and bake for 15 minutes. Drain any excess liquid from the peppers.

While peppers bake, brown the ground beef in a large skillet over medium-high heat. Drain off excess fat.

Add the diced onion to the skillet and cook for about 5 minutes until softened. Stir in taco seasoning, tomato paste, and garlic; cook for 1 minute to combine flavors.

Pour in 2/3 cup water, bring the mixture to a boil, then reduce heat and simmer.

Stir in black beans and diced tomatoes with chilies. Let simmer for 5 minutes.

Spoon the taco filling evenly into the baked pepper halves. Top each with shredded cheese.

Return peppers to the oven and bake uncovered for an additional 15 minutes, or until the cheese is melted and bubbly. Serve warm.