Make the Spinach Sauce: Sautee the onion in ghee, in a large pan, over medium heat for 3-4 minutes, then add garlic, ginger and chilies. Saute until fragrant and golden. Add the mustard seeds, cumin seeds and garam masala and stir two minutes. Lower heat to low. Add the fresh spinach, mint and water. Cover pan, 2-3 minutes, letting spinach wilt. Give a few stirs.
Blend Spinach Sauce: Place the wiled spinach mixture in a blender and add the 3/4 water. Pulse and few times (hold lid down tight). If you want a smooth sauce, blend until smooth. I left a little texture here. Pour it back into the pan, set on low heat.
Combine: Mix in the yogurt, lentils and salt. Adjust salt to your liking, adding more if necessary! You want this slightly salty because you are serving over rice which will mellow it out a lot. For more heat add a pinch of cayenne or chili flakes.
Cook black lentils according to package or try the pasta cooking method: simply boil 1 1/4 cups dry lentils in 6 cups of salted water until just tender, strain. Size of lentil will determine cooking time. Little black lentils take 20-30 minutes.
Feel free to sub other whole lentils for the black lentils. Feel free to sub other greens for the spinach.