In a non-stick pan over medium heat, heat the olive oil. Add the onions and saute until translucent, about 3 minutes. Stir in the uncooked quinoa and lentils. Stir the mixture together. Pour in 3 cups of the broth and stir until well-combined. Lower the heat to low, cover, and let the mixture simmer for about 15-20 minutes, or until the quinoa and lentils have absorbed the liquid and are tender. Add the remaining cup of broth if needed.
Stir in the butter (or more oil). Season with salt and pepper. Serve.