Heat oil in a large pan over medium heat. Add the onion and saute for 4 minutes. Stir in black beans, garlic, cumin, chili powder, salt, and pepper; continue sautéing for 4 minutes. Add tomato, cilantro and hot sauce, if using.
Remove the pan from heat and you can mash slightly with a fork if you like.
Accompaniments: Slice avocado, salsa, lime wedge, plain yogurt, cheddar cheese, blue corn tortilla chip, unsalted canned corn.