Quinoa, black bean and mango salad

I like the combination of flavours in the recipes  in a new cookbook by Moskowitz and Romero, Veganomicon. This one is very  easy and can be any mix of grain, fruit and bean that appeals.

1 mango, peeled and small diced
1 red bell pepper, seeded and small diced
1 cup cilantro, chopped
1 cup scallions, chopped (optional)
2 tablespoons red wine vinegar
2 tablespoons oil (optional)
2 cups, quinoa, cooked
1 (19 ounce) can black beans drained and rinsed, or 1 1/2 cups beans

Combine everything but the bean and quinoa in a bowl and mix together. Then add quinoa and stir into well coated. Fold in black beans. Can be served immediately or let sit, for favours to meld