Heat 1 tablespoon of the oil in a large saucepan over medium heat for 1 minute. Add the scallions and garlic and sauté, stirring occasionally, for 3 minutes or until slightly softened. Add the remaining oil to the saucepan along with the carrots and mushrooms and sauté, stirring occasionally, for 5 minutes or until the carrots are crisp-tender. Add the rice, lentils, salt, coriander, cumin, ginger, and turmeric, and stir to coat. Add the water and bring to a boil over high heat. Adjust the heat so that the mixture bubbles gently, cover, and cook for 15 minutes. Stir in the spinach, cover, and cook for 2 minutes or just until the spinach is slightly wilted. Top each portion with 1/4 cup or so of the yogurt and, if desired, the sesame seeds. This one dish meal serves 4-6.