Canned beans are cheap (and don’t go bad) and the recipe uses produce that can be purchased individually, like onions, carrots, avocados and Serrano peppers.
Heat a large heavy-bottomed pot or Dutch oven over medium heat, add the olive oil and heat through. Add the onion and carrot and sauté, stirring occasionally, until the onions are soft and translucent, about 6 minutes. Add the garlic and sauté for an additional 30 seconds.
Add the cumin, oregano, and Serrano followed by the black beans, vegetable broth and cilantro. Bring to a boil then lower heat to medium-low and simmer, until the soup has thickened, about 30 minutes.
Season to taste with salt. Let the soup cool then add to a blender and pulse until the mixture is pureed and smooth. Return the mixture to the pot.
For serving:
In a small bowl stir together the tomatoes, Serrano peppers and olive oil. Season with salt and set aside.
Ladle soup into warmed soup bowls and top with sour cream, avocado and tomato salsa.
Notes
Bloom the ground cumin and oregano in the olive oil with the garlic and serrano pepper for 30–60 seconds to deepen their flavor without burning them before adding the beans and broth.