If using frozen mango chunks, put them in a bowl with warm water to thaw.
Combine the chopped onion, diced jalepeno, chopped cilantro, chopped red bell pepper, quinoa and black beans in a bowl. Cut the thawed mango into small 1/2 inch chunks and add the to the bowl.
Stir dressing ingredients together and toss with salad.
Roughly chop spinach leaves into smaller pieces. Toss with the rest of the salad, or as I like to do when using a salad platter, put a bed of spinach beneath the quinoa salad. Just before serving, add chopped avocado.
Notes
Meal Prep Tip: Cook large batches of quinoa or rice to use throughout the week. Also freeze small bags of 1 or 2 cup portions. You can thaw it quickly in the microwave or under hot water, so you can toss it quickly into salads like this.