In a food processor with a splash of water, purée ½ of the black beans until a paste is formed. Set aside.

Heat the olive oil in a large skillet over low heat. Add the diced white onion and cook, stirring occasionally for 5-7 minutes. Add three cloves of the minced garlic and cook 2 minutes. Add the ground beef and cook until browned. Stir in the tomato paste, cumin, chili powder, minced chipotle pepper, and a generous pinch of salt. Fold in the puréed black beans with ½ cup of water. Stir to combine. Raise the heat to high and bring to a gentle boil. Stir, then lower the heat and simmer, covered, stirring occasionally, for 30 minutes, until the mixture has thickened. Taste and add more salt or chili powder as needed.

In a large bowl, combine the tomatoes, minced red onion, jalapeño, cilantro, and remaining 2 cloves of minced garlic. Stir in a pinch of salt and the lime juice. Taste the pico de gallo and adjust the seasoning if needed.

Assemble the burritos by scooping ¼ cup of the beef and black bean filling into each warmed tortilla. Top with remaining black beans, avocado, grated cheese, and/or lettuce, and serve with pico de gallo.