1.5cupscooked black beans(or one 15 oz. can, drained and rinsed)
Heat the olive oil in a 3.5 quart skillet or Dutch oven over medium heat. Sauté the onion and pepper until softened, about 8 minutes.
Add in the garlic, cumin, chili powder, and cayenne pepper, if using, and sauté until fragrant, about one more minute.
Add in the chopped tomatoes (with their juices), salt, quinoa, red lentils, water, and black beans. Stir well and bring the liquid to a boil. Cover and lower the heat to a simmer, cooking until the quinoa and lentils are tender, about 15 minutes.
Remove the lid and fluff with a fork. Serve warm with a topping of fresh cilantro, avocado slices, and radishes, if desired.