Combine the lentils, turmeric and 7 cups of water in a medium saucepan and bring to a boil. Reduce the heat to medium-low, cover, and simmer until tender, about 25-30 minutes. Drain well, reserving ¼ cup of the cooking liquid. Transfer to a large bowl and set aside.
While the lentils are cooking, heat 1 tablespoon of the oil in a large skillet over medium heat. Add the onion, garlic, cumin, coriander, 1 teaspoon salt, and ½ teaspoon pepper and cook until softened and golden, about 5 minutes. Add the reserved lentil cooking liquid and cook, stirring, until most of it is absorbed, about 2 minutes. Transfer the onion mixture to the bowl with the lentils. Add the carrot, parsley, raisins, lemon juice, lemon zest, and the remaining 1 tablespoon oil and toss to combine. Season to taste with salt and pepper and keep warm.
To cook the steak, combine the oil, spices, garlic, ¾ teaspoon salt, and ¼ teaspoon pepper in a small bowl. Rub the mixture evenly over the steak. Heat a grill (or grill pan) to medium-high. Brush the pan with oil and cook the steak for 3-4 minutes each side for medium rare. Transfer to a board, cover loosely with foil, and rest for 5 minutes. Thinly slice the steak against the grain and serve with the lentils.