Add the lentils to a medium-sized sauce pan, add 5 cups water and bring to a boil.
Once the water has come to a boil, add ½ of the onion, turmeric, red chili powder, salt and pepper.
Give the daal a quick stir, cover it with a lid and let it cook undisturbed for 35-40 minutes, until soft.
About 20 minutes in, start getting the tadka (tempering) ready. Heat oil in a frying pan. Once it begins to shimmer, add the remaining chopped onion. Fry on high heat until it starts to brown.
Add the garlic and fry until it slightly changes color. Add cumin seeds and stir until fragrant (while keeping an eye on the onions and garlic, making sure they don’t burn). Add chilies and fry for a few seconds. Remove from heat.
Once the tadka is ready, check your daal to see if it's done. If the lentils are soft, remove from stove and place daal in serving dish. Pour the tadka (including the oil) over it.
Serve with rice and achaar (pickles).