Heat half of the oil in a skillet or a pan over medium heat. Cook the onion and garlic about 3 min until the onion is soft and translucent, with occasional stirring, paying attention not to let them burn. Remove from pan and set aside. Pour the remaining oil into the same pan, heat over medium heat, and add the ground meat. Cook about 5 min, stirring occasionally with a wooden spoon, until the meat loses its pink colour.
Put the cooked onion and garlic back into the pan. Add the diced tomatoes, tomato paste, diced bell pepper, minced chili pepper, cumin, and brown sugar. Pour in the warm broth. Cover and cook over very low heat 1 ½ h, checking occasionally that the mixture stays moist. Add water if necessary.
Drain the beans, rinse them and drain again. Add them to the pan, mix well, and cook an additional 8-10 min. Add salt and pepper to taste. Sprinkle with freshly chopped cilantro leaves, garnish with lime wedges, then serve.