Step 1Rinse the lentils thoroughly and soak them in 1 1/3 cups of water, covered, for about 1 hour. (They will probably absorb all the water.) Transfer the lentils and any remaining water to a heavy-bottomed pot. Add 1 1/2 cups of water and bring to a boil over medium heat. Reduce the heat and simmer until the lentils are soft but not mashed, 20 to 25 minutes. Turn off the heat and cover the pot.
Step 2While the lentils cook, heat the oil in another heavy-bottomed pan over medium heat. Add the garlic and cook for 1 minute. Add the onion and cook until it turns light brown, about 10 minutes. Add the tomato and cook until soft, 5 minutes. Drain the lentils and add them along with the spinach and chile. Add the salt. Stir and cook for 2 minutes on medium-high heat. Serve hot, garnished with the ginger.