ash and soak the peanuts in 1/2 cup water for 3 to 5 hours
Pressure cook the soaked peanuts along with water and salt on medium heat , turn off the heat after 1 to 2 whistles
Finely chop the onion and green chillies and keep it ready.
Seasoning:
Heat the oil in a pan on medium heat, once hot add mustard seeds, after it pops add urad dal and hing . Fry it until the dal turns golden brown, and also add curry leaves.
Once the dals turn golden brown add turmeric powder, green chillies, fry it for few seconds, then add chopped onion fry it for a minute and then add cooked peanuts, jaggery and pinch of salt, stir it for 2 to 3 minutes,
Now add chopped coriander leaves, mix it and turn off the heat
Finally squeeze the lemon juice, add coconut and mix it well and Peanut / groundnut usli is ready to serve.
Notes
You can use the cooked peanut water to make rasam or sambar.