Pick and wash the lentils, and cook them in only as much water as they will absorb. Peel, wash, and cut up the mushrooms, chop fine the onion, and fry both in the butter. Add them to the lentils now cooking; also the lemon juice and seasoning. When the lentils are quite soft, the whole should be a fairly firm pureť. Let it cool, and meanwhile make a paste of 6 ounces of Allinson fine wheatmeal and 2 ounces of butter or vege-butter and a little water. Roll the paste out thin, cut into squares of about 4 inches. Place some of the lentil mixture in each, moisten the edges, turn half over, and press the edges together. Bake for 15 minutes in a floured tin, and serve with brown sauce, vegetables, and potatoes.