Add oil to a medium dutch oven and place over medium heat. Add the chopped onion and carrot. Cook the vegetables while stirring occasionally until tender for about 10 minutes.

Add the garlic, cumin, oregano, salt, and red pepper flakes to the vegetables and saute for 2 minutes.

Pour the broth and lime juice, then add the black beans. Let it come to a boil over medium-high heat. Once boiling, reduce the heat to low. Place the lid and let it simmer for 25 minutes while stirring occasionally.

Ladle two cups of soup into a blender, open the vent, and blend the soup until smooth. Alternatively, you can use an immersion blender. Pour it back into the pot with the remaining soup.

Cook the soup without the lid on until it thickens for about 10 to 20 minutes.

Serve with avocado slices, a dolop of sour cream, and chopped cilantro.