To cook Lentils and rice separately for a fluffier mujadara:

1.  Heat the olive oil in a medium pot. Add the onions and cook over medium-high heat for about 20-30 minutes, or until golden, stirring frequently.  If you see that the onions are starting to burn or stick to the pan, add 2 tablespoons of water and continue cooking. Add more water ( 2 tablespoons at a time), if necessary. Set the onions aside in a medium bowl.
2. In a medium saucepan, bring 4 cups of water to a boil. Add the lentils and 1 tsp of the salt
3. Bring to a boil and lower the heat to medium. Cook, covered, until tender about 20-25 minutes. Depending on which type of lentils you're using, they might need more cooking time. Lentils should be tender, but not mushy. Keep an eye on the lentils making sure the water doesn't all evaporate, since the lentils can burn. Once they are soft, drain them and let them cool slightly.
4. While the lentils are cooking, bring 1.5 cups of water to a boil in a separate pot. Add 1 tsp of the remaining salt. Add the rice and bring to a boil. Cover the pot and lower the heat to simmer for 20 minutes or until all the water has been absorbed and the rice is cooked.
5. Once both rice and lentils are cooked, gently combine them in a large bowl with the rice and the  cooked onions.
6. Serve with a tomato-cucumber salad  or any salad of your choice
7. You can also serve it with some plain yogurt seasoned with salt and lemon to taste and sprinkle with some dried mint or oregano (optional).

To cook the Mujadra in one pot

1. Heat olive oil in a medium pot. Add the onions and cook over medium-high heat for about 15 minutes, or until slightly golden, stirring frequently.  If you see that the onions are starting to burn or stick to the pan, add 2 tablespoons of water and continue cooking. Add more water ( 2 tablespoons at a time), if necessary. 
2. Add 2 1/2  cups of water to the onions, and bring to a boil. 
3. Add the lentils and 1 tsp of the salt. Bring to a boil, uncovered, and boil for about 10-12 minutes or until all the water is almost absorbed and the lentils are about half-cooked.
4. Add an additional 2 1/2 cups of water, bring to a boil, add parboiled rice and the remaining 1 tsp of salt. Bring to a boil and lower heat and simmer, covered, for 20 -25 minutes
5. Turn off the heat and let the mujadara sit, covered, for 10 minutes. Remove the lid and fluff it up with a fork
6. Serve with a tomato-cucumber salad  or  Fattoush Salad.
7. Alternatively , you can serve it with plain yogurt with diced cucumbers seasoned with salt and lemon to taste and sprinkle with some dried mint or oregano (optional).