Soak the lentils in water to cover for 1 hour. Drain, place in saucepan or casserole, cover with water by 2 inches, and bring to a boil. Add 1/2 teaspoon of the salt, reduce heat, and simmer 30 minutes, until just about tender. In another casserole, heat 1 tablespoon of the olive oil and saute the chopped onion until it begins to color. Add the cumin seed and cinnamon, stir together, and add the rice. Stir to coat with oil and add 2 cups water and the lentils with their liquid, plus about 1/4 teaspoon salt and pepper to taste. Stir together, bring to a boil, reduce heat, cover, and cook 20 to 25 minutes or until the liquid is absorbed. Meanwhile, brown the sliced onion in the remaining 1 1/2 teaspoons of olive oil. When the rice and lentils are cooked, transfer to a platter and strew the browned onions over the top.