Soak lentils in water for 3 hours; drain. Soak rice in water for 1/2 hour; drain. Saute onions in a large skillet for about 15 minutes, or until very brown and crisp. Remove onions to a plate lined with paper towels to drain. Turn heat to medium-high and add lentils and rice to skillet; saute quickly in the browned-onion-flavored oil, adding cumin, salt and pepper. Add 3 cups of water and bring to a boil. Cover very tightly and then cook on very low heat for about 20 to 25 minutes. To serve, fluff up rice and lentils and top with the crispy browned onions.