Fry onions, bell peppers and sweet potatoes in the oil until the onions begin to soften, about 4-5 minutes. Add garlic and sauté for 2 minutes longer.

Add the beans, tomatoes, yogurt, taco spice, chili powder, cumin, bay leaves and salt, stir to combine. Cover with just enough water to cover beans. (About 1-2 cups.)

Bring to a boil. Reduce to a simmer and cook uncovered for 1 hour, stirring often to make sure nothing sticks to the bottom.

Serve with coriander, green onions, avocado, rice and tortilla chips.