Rinse the quinoa well and place in a pan with about double the volume of water. Bring to the boil, cover, reduce the heat and gently simmer for 10 mins or until the grain unwraps itself. Turn off the heat and leave to cool slightly, then drain any remaining water.
Season the quinoa, stir in the lemon juice and oil and leave to cool fully. Stir in the other ingredients, then serve.