Lightly oil a rectangular casserole and set aside. About 9" x 12". The casserole cooks better in a shallow dish such as this.
In a skillet heat one tablespoon oil to medium high and then turn it down to medium and saute the onion until it is translucent - about 10 minutes.
To the casserole sprinkle in the rice, lentils, carrots, tomato, spices and the sauteed onion.
Heat the 3 cups of vegetable broth to a boil.
Be careful and pour the broth over everything in the casserole dish.
Stir until all is evenly dispersed. The rice and lentils will settle on the bottom.
Cover with the lid or cover tightly with foil. Leaving enough foil to go over the edges, liberally.
Bake at 325 degrees for 60 to 70 minutes.
Check after an hour and see if the liquid has absorbed and the rice is tender. It will still be very moist.