1.Soak lentils in cold water for 30 minutes.
2.In a large frying pan, melt butter, add onion and cook, stirring, over medium heat for about 2-3 minutes, or until onion has softened. Add rice and drained lentils, cook, stirring, for a further 2 minutes.
3.Stir in stock and water. Bring to the boil; reduce heat to low, simmer, uncovered, stirring occasionally, for about 30 minutes, or until liquid is absorbed and lentils are just tender. Remove from heat, stir in coriander.
4.Stand covered in pan for 10 minutes before serving.
Pilaf can be prepared several hours ahead. Transfer pilaf to an ovenproof dish, cover with foil and refrigerate. Warm in oven as required.Note