Heat the olive oil in a large pot or Dutch oven over medium heat. Add the chopped onion and sauté until softened and translucent, about 5 minutes.
Add the minced garlic and ground cumin to the pot. Cook for 1 minute until fragrant.
Stir in the rinsed basmati rice and brown lentils, toasting them lightly in the spices and oil for about 2 minutes.
Pour in the tomato sauce and vegetable broth, then add the salt. Stir well to combine and bring the mixture to a boil.
Reduce the heat to low, cover the pot tightly with a lid, and simmer for 30-35 minutes, or until the liquid is absorbed and the lentils and rice are tender.
Remove the pot from the heat and let it rest, covered, for 5 minutes. Fluff the pilaf with a fork, garnish with freshly chopped parsley, and serve warm.