Soak the lentils in cold water to cover for 2 hours. Drain well. Combine the lentils, rice and onions in a large casserole. Stir in remaining ingredients, then cover. Bake in a preheated 220ºC . oven for twenty-five minutes. Stir rice and lentils gently to mix well, then bake for 20 minutes longer or till the rice is tender and the liquid absorbed. One tsp curry powder may be added if you like.