Meanwhile, in a large skillet, toast the pine nuts over moderate heat, stirring, until fragrant, about 2 minutes. Transfer to a plate. Heat the 3 tablespoons of olive oil in the skillet. Add the garlic and onion and cook over moderate heat until softened, about 5 minutes. Add the carrots and cumin, cover and cook over low heat until the carrots are just tender, about 5 minutes. Stir in the quinoa and vinegar and season with salt and pepper.