Clean,shell and devein the prawns. Mix lemon juice, salt, pepper, chilli powder and mustard paste and apply the paste to the prawns. Add a little olive oil to the marination and mix well. Keep the prawns aside for two hours.
Arrange the marinated prawns on the skewers (sheekh) and cook in a clay oven (tandoor) for eight to 10 minutes or till done. Serve hot with greens and onion rings.