Press the sauté button, add the oil and allow it to heat up for a minute. Add the cumin and mustard seeds. Once the cumin seeds brown and the mustard seeds pop, add the onion and Serrano pepper. Stir-fry for 6-7 minutes, or until the onions begin to brown.
Add the garlic, ginger, potatoes and and stir-fry for 30 seconds. Pour ¼ cup water into the pot, secure the lid, close the pressure valve and cook for 3 minutes at high pressure.
Open the valve to quick release any remaining pressure.
Remove the lid, stir the potatoes, then add the cauliflower florets and sprinkle the spices on top of the florets. Secure the lid, close the pressure valve and cook for 1 minute on high pressure. Quick release remaining pressure.
Remove the lid, mix well, garnish with cilantro and serve.