In medium saucepan, combine water and lentils. Bring to a boil. Reduce heat; cover and simmer 5 minutes. Add rice, onion and salt; mix well. Cover; simmer an additional 15 to 18 minutes or until liquid is absorbed and lentils and rice are tender. Remove from heat; cool 10 minutes.
Heat oven to 350°F. Grease 8x4-inch loaf (1 1/2-quart) baking dish. (Do not use metal pan). Add 1/4 cup of the spaghetti sauce and remaining ingredients to lentil mixture; mix well, mashing mixture slightly while mixing. Press mixture firmly in greased dish.
Bake at 350°F. for 40 to 45 minutes or until top is golden brown and loaf is firm. Remove from oven; cool 10 minutes. Loosen edges with knife, if necessary; invert loaf onto serving platter.
In small saucepan, heat remaining spaghetti sauce for 3 to 4 minutes or until hot. To serve, slice loaf; place on individual serving plates. Spoon warm sauce over each slice.