Step 1: Preheat your oven to 375°F (190°C) to ensure even baking.
Step 2: Unroll the crescent dough and separate it into triangles. Press each triangle into the cups of your muffin tin.
Step 3: In a large skillet, brown the ground beef over medium heat. Drain excess fat, add taco seasoning and water, and simmer for 5 minutes.
Step 4: Stir in the drained black beans and heat through for 2-3 minutes.
Step 5: Fill the crescent-lined cups with the beef and black bean mixture, filling them about three-quarters full.
Step 6: Top with shredded cheddar cheese and diced tomatoes.
Step 7: Bake for 15-18 minutes until the crescent dough is golden brown and cheese is bubbly.
Step 8: Let cool for a few minutes, garnish with cilantro if desired, and serve.