We like the black-bean and chickpea combination, but feel free to use your favorite beans.
In a Dutch oven or 5-quart saucepan with a lid, heat oil over medium. Add onion and garlic and cook, stirring occasionally, until tender, 5 to 7 minutes. Add squash, bell pepper, and chile powder; season with salt and pepper and cook, stirring 1 minute. Add 1/2 cup water. Cover and simmer until vegetables are crisp-tender, about 7 minutes.
Stir in tomatoes and their juice, breaking them up with a spoon; add chickpeas, black beans, 1/4 cup cilantro, and 1/2 cup water. Bring to a boil. Reduce to a simmer, partially cover, and cook until lightly thickened, about 20 minutes.
Season with salt and pepper. Stir in remaining cilantro and spoon into serving bowls. Serve with lime wedges.
Because they're high in soluble fiber, beans are a cholesterol fighter's best friend.