Make the spice mix: grind together cumin, coriander, fenugreek, and peppercorns and set this spice mix aside.
Make the curry: Place chicken, onions, ginger, garlic, tamarind paste, 1 cup coconut milk, salt, turmeric, cayenne, and water into the inner liner of your Instant Pot or Pressure Cooker.
Add the spice mix and stir well.
Cook for 6 minutes at high pressure. At the end of the cooking time, allow the pot to rest undisturbed for 10 minutes and then release any remaining pressure.
Add in the coconut milk and stir well.
Garnish with cilantro and serve with rice or naan.
Most of the carbs in this recipe come from the onions. If you want to cut carbs even more, reduce the onions to 3/4 cup - 1 cup.