Wash the toor dal and set a side. Turn on the saute mode on your instant pot and heat oil, mustard seeds and cumin. Let the mustard pop. Add the garlic and curry leaves and saute for 30 seconds and then add the chopped onion.
Add the onion and saute for three minutes until onion turns soft. You can add splashes of water to avoid onion from burning. Add turmeric and give a mix.
Now add washed toor dal, chopped dill leaves, salt, sugar, sambar powder and water. Give a mix, de glazing the pot to avoid burnt sign.
Cancel the saute mode, close the vent and close the lid and turn the vent to sealing position. Press pressure cooker (manual mode) and adjust the cook time to ten minutes. Once done, let the release the pressure after ten minutes.
Add tamarind, add more water if required and cook on saute for couple of minutes. Taste the dal and adjust the seasoning.