Mamas MJedrah Rice and Lentils

Name: Mama's M'Jedrah (Rice and Lentils)
Ingredients: 1 cup uncooked lentils; 5 cups water; 2 tablespoons coarse salt; 2 cups long grain rice; 3 tablespoons butter, chopped; 3 medium onions, halved and sliced; 1/3 cup oil (I used one part olive and one part vegetable)