Heat the oven to 425F. Place the jalapeno, onion, and garlic in a small dish. Roast the vegetables until charred at the edges and softened, for about 30 minutes. Let cool slightly to handle.

To a food processor or blender, add the beans, roasted jalapeno and onion, garlic (remove the skin), cumin, juice of the entire lime, and olive oil. Blend until smooth, and taste: add salt to your preference and more olive oil if needed to smoothen the dip.

Serve topped with the lime zest. Enjoy!