| 2 teaspoons extra-virgin olive oil |
| 1 medium yellow onion, diced (about 1 1/2 cups) |
| 2 teaspoons ground ancho chile pepper (see Ingredient note) |
| 1/2 teaspoon ground cumin |
| 1/2 teaspoon dried oregano |
| 2 15-ounce cans black beans, rinsed |
| 1 tablespoon tomato paste |
Ingredient Note: Ancho chile peppers, one of the most popular dried chiles used in Mexico, are dried poblano peppers. They have a mild, sweet, spicy flavor. Ground ancho chile pepper can be found in the specialty-spice section of large supermarkets, or substitute ground chili powder with a pinch of cayenne. |