In large pot (6 quart), add olive oil. Add diced onion and cook over low/medium heat until tender. Add 2 cups of the broth and the 2 cans of refried beans. Stir/whisk until the refried beans have thinned out in the broth. Add black beans, tomatoes, corn, cumin, vinegar, garlic, and thyme. Stir until well combined. Add the remaining broth until soup is to your desired thickness. Add bay leaves, bring soup to simmer and simmer for 30 minutes. Do not eat bay leaves(remove whole bay leaves before serving)
Tortilla chips
If you have carnivors in your house you can also add chicken for a non-vegetarian version. If you wanted to change the recipe to incorporate raw chicken, you cook the onions and the chicken together until onions are tender and the chicken is fully cooked and then add the rest of the ingredients