Pour quinoa into a bowl of cold water and wash it, rubbing it between your hands. Drain and repeat until the water is clear. Bring 3 quarts of salted water to a boil in a large saucepan. Add the quinoa, stir once and return to a boil. Cook, uncovered, over moderate heat 10 minutes. Pour through a strainer and drain well. Transfer to a large bowl.
Meanwhile, heat the olive oil in a large saucepan over moderate heat. Add the carrot and saute for 1 minute. Stir in the scallions and cook for another minute. Add the bell pepper, salt and pepper and saute for about 2 minutes. Add the peas and stir to combine. Add the quinoa, chopped nuts and thyme and stir again to combine. Serve immediately.