Rinse lentils until water runs clearly through them, then cook for ~15-20 minutes over medium heat in 4 cups of water. As the lentils cook, add salt and a generous amount of turmeric. You want the lentils to break down and become quite thick.

While the lentils simmer,  heat the ghee or oil in a large pan. Add onions or shallots and cook ~3 minutes until soft. Add the garlic and ginger root and cook for ~2 minutes more.

Spice. Remove from heat and add your personal blend of spices, stirring to coat everything in the pan. Toasting the spices in this way releases their flavors, but you want to take care never to burn the spices over high heat, should your dish take on a bitter quality. You can be generous with turmeric, but should be sparing with cloves, cumin, and ginger, all of which can overpower in large quantities. 

Return to heat and add the can of tomatoes, stirring well. The lentils should be completely collapsed by now and all the water evaporated from the pot. Pour the lentils into the pan with the tomatoes and simmer for ~10-20 minutes, taking care not to let the dahl stick to the bottom of the pan.

When ready, add lemon juice and the spinach, stirring and folding so the spinach becomes submerged in the dahl. Cook at least 5-10 minutes more until the spinach is fully integrated. Serve over basmati rice and with naan with a garnish of cilantro.

A note on naan: most any storebought naan will do. Lay it out on a pan, cut it into slivers, and sprinkle with a good olive oil, sea salt, and pepper, and place under broiler until crispy. Really takes this dish to the next level.