Combine the lentils, 2 cups water, 1 teaspoon salt, the cumin, and garlic powder in a pot over medium heat; bring to a simmer, reduce heat to low, and cook until the lentils begin to soften, 20 to 30 minutes.
Stir the rice, 3/4 cup water, 1 teaspoon salt, and the olive oil into the lentils. Cover the pot and continue cooking until the lentils and rice are tender, about 40 minutes.
Heat the cooking oil in a skillet over medium heat; cook the onions in the oil until browned, 7 to 10 minutes.
Spread the onions over the rice and lentil mixture to serve.
