Heat 2 tablespoons of extra-virgin olive oil in a large Dutch oven over medium heat. Add 2 medium chopped yellow onions, 3 finely chopped celery stalks, 1 large thinly sliced carrot, and a pinch of salt.
Cook for 10-15 minutes, until soft. Stir in 6 minced garlic cloves, 4½ teaspoons of ground cumin, and ½ teaspoon of red pepper flakes for 30 seconds.
Add 1.7kg of canned black beans, rinsed and drained, and 4 cups of low-sodium vegetable broth. Simmer gently for about 30 minutes, until the beans are very tender.
Blend about 4 cups of the soup until smooth and stir it back into the pot. Add 2 teaspoons of sherry vinegar and season with salt and pepper.
