In a large pot, bring 4 cups of water or vegetable broth to a boil. Add the rinsed lentils and reduce the heat to medium-low. Let the lentils simmer for 15 minutes, or until they are tender but not mushy. Drain any excess liquid and set aside.

While the lentils are cooking, heat 3 tablespoons of olive oil in a large skillet over medium heat. Add the thinly sliced onions and cook for 15-20 minutes, stirring frequently, until the onions turn a deep golden brown and caramelized. Be patient, this step is key to developing rich flavour.

Remove half of the caramelized onions from the skillet and set them aside for garnishing later. Leave the remaining onions in the skillet to continue building the flavour base of the dish.

Add the rice to the skillet with the onions and stir to coat the grains in the oil and onion mixture. Toast the rice for 2-3 minutes, ensuring the grains are well mixed with the onions and infused with flavour.

Stir in the cooked lentils, cumin, cinnamon, salt, and black pepper. Mix everything together, allowing the spices to coat the lentils and rice evenly for a deep, aromatic taste.

Pour 2 cups of water or broth into the skillet, bringing the mixture to a gentle simmer. Cover the pot with a tight-fitting lid, reduce the heat to low, and let the Mujadara cook for 15-18 minutes, or until the rice is fully cooked and all the liquid has been absorbed.

Once the rice and lentils are cooked, remove the pot from heat and let it rest, covered, for 5 minutes to allow the flavors to settle and the rice to become fluffy.

Fluff the Mujadara with a fork and transfer it to a serving dish. Garnish generously with the reserved caramelized onions and a sprinkle of fresh parsley. Serve with lemon wedges on the side for an optional citrus boost that enhances the earthy flavors of the dish.