Step 1

Heat oil in a large straight-sided skillet over medium. Reserve 1/4 cup diced onion; add remaining onion to skillet along with garlic. Season with salt and cook, stirring, until tender, 4 to 6 minutes.

Step 2

Add chipotle, chili powder, cumin, and tomatoes with their juices; cook, stirring, 2 minutes. Add beans and cooking liquid; bring to a simmer. Cook until slightly thickened, 15 to 18 minutes. Season to taste. Sprinkle with cheese, cover, and cook until just melted, about 2 minutes.

Step 3

Remove from heat; top with reserved onion, avocado, and cilantro, and serve with sour cream and tortillas.