Heat the olive oil in a pan over medium-high heat. When hot add in the onions and garlic and sauté for about 5 minutes until the onions turn translucent and begin to brown. Add the black beans, BBQ sauce, and salt and pepper. Heat through.
Pile the beans on bread, toast, or a tortilla, garnish with cilantro, then drizzle a little extra BBQ sauce on top.
BBQ Black beans can be prepared ahead of time. If bringing to work, I like to bring them in a separate container, so I can heat them up before piling them on the bread, If that seems too fussy, this sandwich is still great cold too!