If you haven’t already, cook the quinoa according to package directions. Drain in a strainer and rinse.
Meanwhile, peel the sweet potato and dice it into 1/2-inch or smaller pieces.
Steam until very tender, but not mushy. (Or, if you have leftover baked sweet potato, you can just peel it and chop it up.
Toss together the potato, quinoa, bell pepper, and onion. Sprinkle with salt and pepper.
Whisk the oil and vinegar together and toss the salad with about half of this mixture. Add some or all of the rest to taste.
Taste and adjust the seasoning, sprinkle with chives or parsley and serve.
from How to Cook Everything Vegetarian by Mark Bittman