When people speak of "daal", they often refer to masoor daal (red lentils). While masoor daal is delicious, it's popularity often comes at the expense of equally flavorful lentils. My personal favorite is "kalee daal" or green lentils that were a lunch staple in my home in Pakistan. We used to enjoy them alongside rice and pickled mangoes. But they go equally well with salad greens, or by themselves as a starter soup. —Pakistan Eats
Add the lentils to a medium-sized sauce pan, add water and bring to a boil.
Add half of the sliced onion, and salt, pepper, turmeric and red chili powder.
Once the water comes to a boil, turn the heat down to low, cover the pot and leave it undisturbed for forty minutes.
30 minutes in, start to get the tempered spices ("tadka") ready. Heat vegetable oil in a saucepan and add onions. Fry the onions on medium heat till they are medium brown. Add garlic to the saucepan and fry till medium brown. Add cumin seeds and dried red chilis. Fry for a few seconds.
Once the lentils are done, serve in a bowl. Top with tempered spices and oil.