Heat olive oil in a pot over medium heat; cook and stir onion and garlic until onion has softened, 5 to 7 minutes. Add ginger and stir until fragrant, 1 minute. Add brown rice and stir to coat rice with oil.
Stir lentils, cumin, salt, black pepper, and cinnamon into rice mixture; cover with water. Place lid on pot and simmer over low heat until lentils are tender and rice has absorbed the water, about 45 minutes.