In a small saucepan, cook quinoa with water and a pinch of salt. Bring to a boil then cover and simmer for about 15 minutes. Remove from heat and let it sit for 5 minutes then remove lid, fluff and let cool in a bowl.
Toast cumin seeds in the same saucepan for about 2 minutes.
In a blender, combine cumin seeds, lime juice and oil. Season with salt and pepper to taste.
In a large bowl combine black beans, peppers, cilantro and onions. Add dressing and blend well.
Add quinoa, mix well and season with salt and pepper if desire.