The mujadara, a pilaf of lentils, onions, and bulgur or rice, can be served over the salad hot, warm, or room temperature. Serve this dish as a side or a main dish along with other roasted or steamed vegetables, pita or flatbread, and labneh.
First, par-cook the lentils. Place the lentils in a small saucepan with 2 cups of water and a pinch of salt. Bring to boil over high heat. Reduce heat and simmer until lentils are par-cooked, 7-10 minutes. Remove from heat. Be careful not to overcook here; the idea is to par-cook the lentils.
In a large, heavy sauté or sauce pan (with a lid), heat the canola oil over medium high heat. Add the onions and cook until deep golden brown, about 20 minutes, stirring frequently to avoid burning, though some charring will occur in order to get them all browned and that's just fine. Sprinkle with a pinch of salt as the onions cook.
Take the onions off the heat and add 2 cups of water. Place back on the heat and bring to a boil, then reduce heat and simmer for 5 minutes. The liquid will take on the deep golden color of the onions and the onions will continue to soften.
Add the bulgur or rice and par-cooked lentils (and their liquid) to the onion mixture. Cover and bring to a boil. Sprinkle with a pinch of salt and pepper. Reduce heat to low and cook until the liquid has been absorbed and the rice and lentils are cooked through. The texture of the rice and lentils is somewhat al dente. Take care not to overcook or the mixture will become mushy. Remove from heat and season to taste with salt and pepper, and drizzle with olive oil.
For the salad, make the vinaigrette by whisking the lemon juice, olive oil, garlic powder, salt and pepper in a small bowl. Toss the arugula and scallions with just over half of the vinaigrette. Dress the tomatoes and avocado separately with the vinaigrette.
Arrange the arugula on a platter, and place the tomatoes and avocadoes around the perimeter. Spoon just over half of the cooled mujadara in the center of the platter and save the other half to eat later, or serve it alongside--just don't overwhelm the salad with so much mujadara that you can't see the salad!
Drizzle olive oil over the mujadara (again; it will absorb and be delicious). Serve immediately.