This Mexican-inspired soup gains so much flavor in a short amount of time. Smarts: Be sure to cook the vegetables very well before adding the stock - that's the key to building a great base of flavor.
Heat a Dutch oven or large saucepan with oil over medium-high heat. Add carrots, onions, garlic, and coleslaw mix. Season with some salt and cook until the coleslaw cooks down and begins to soften, 5 to 7 minutes.
Stir in the mushrooms and continue cooking until the mushrooms are soft and the vegetables are starting to caramelize on the bottom of the pan, 8 to 10 minutes more. (Add some water if the vegetables get dry and start to stick to the bottom of the pan.)
Stir the tomato paste, chili powder, oregano, and hot sauce into the vegetables and cook until fragrant, ~2 minutes.
Pour the stock into the pan, scraping up any browned bits on the bottom of the pan. When the stock begins to simmer, add the beans. Cover the pot with a lid and simmer for 5 to 7 minutes to let the flavors come together.
Remove the lid and stir in the cooked rice until heated through. Taste the soup and season with some more salt and pepper or hot sauce.
Divide the soup between bowls. Top with sour cream and cilantro leaves. Enjoy!