Press the sauté button, add oil and allow it a minute to heat up. Add the cumin and mustard seeds. Once the cumin seeds brown, add the onions and Serrano pepper. Stir-fry for 5-6 minutes, or until the onions begin to brown.
Add the ground meat, garlic and ginger and cook until the meat is mostly browned.
Add the spices, give everything a good mix, then add the vinegar, water and potatoes.
Secure the lid, close the pressure valve and cook for 10 minutes at high pressure.
Quick release pressure.
Garnish with cilantro if desired and serve.