Sauté onions in the olive oil with salt, pepper, and a healthy shake of cumin. Rinse the lentils, add to the water with salt and pepper, bring to a boil, cover and cook until the lentils are tender, about 20 minutes. If you start these steps at the same time the onions should be caramelized when the lentils are cooked. Add the onions, oil, and uncooked rice to the lentils and simmer for another 20 minutes, until all the water is absorbed and the rice is cooked. Season at the end with salt, pepper, and cumin to taste.
This is one of those things that has no right being as healthy, heartwarming, cheap, or easy to make as it is. Good for college students trying to learn how to cook because it's almost impossible to mess up. I mean it's basically Arabic rice and beans, after all. If you're upset with my romanization of mjedra, I'm sorry and I don't know enough HTML to type in the Arabic letters.