Rinse the daal/ lentils and add to the Instant Pot along with the bouillon cube, chicken powder, turmeric, coriander powder, cumin powder, Kashmiri chili powder, and diced tomatoes. Add enough water to cover the lentils by about an inch.

Once the cycle is done and pressure has released, open the lid and check the consistency. If you prefer a thinner daal, add 1 cup of water, switch to the Sauté setting, and cook for an additional 5 minutes, stirring occasionally. Adjust to your preferred consistency.

While the Instant Pot has about 5 minutes left on the timer (or once the daal is resting), start your tarka. Heat a small pan over low heat and add your butter, ghee, or oil.
Add cumin seeds, mustard seeds, and nigella seeds to the warm fat. Keep the heat low — you want a gentle sizzle, not a flash fry. This is what allows the spices to infuse properly into the oil.
Add the thinly sliced garlic and Serrano pepper. Continue cooking on low until the garlic turns light golden brown — watch it closely as it goes from golden to burnt quickly. Add the chili flakes, stir briefly.

Immediately pour the entire tarka over the cooked daal. Stir to combine and serve hot.