Prep the Onions: Slice the onions into moon shapes. In a mixing bowl, combine the flour and cornstarch. Toss the sliced onions in the flour mixture and let them sit for about 10 minutes.

Fry the Onions: In a skillet, heat 1 cup of olive oil over medium-high heat. Once hot, add the onions in batches, ensuring not to overcrowd the skillet. Fry until they're brown and crispy, approximately 15 minutes. Remove the onions and place them on a plate lined with paper towels to drain excess oil.

Prepare the Lentils: In a large pot, rinse the lentils, then add 5 cups of water. Bring to a boil. Once boiling, stir in the cumin, turmeric, salt, and 1 tablespoon of olive oil. Add one cup of the fried onions to the lentils and reduce the heat to medium-low. Allow the lentils to simmer until they're tender, around 15 minutes.

Prep & Cook the Rice: While the lentils are simmering, wash the rice and let it soak in warm water for about 20 minutes. Drain the rice, then add it to the pot with the lentils. Check the water level; you should have roughly half an inch of water covering the lentil and rice mixture. If needed, add a bit more water.

Finish Cooking: Reduce the heat to low, cover the pot, and let the mixture cook for about 25 minutes, or until the rice is tender. Once done, turn off the heat and let it sit, covered, for an additional 10 minutes to steam.

Serve: Transfer the Mujadara to a platter. Top with the remaining crispy fried onions and optionally sprinkle with sumac for added flavor. Enjoy!