Heat 1 tablespoon of butter over medium high heat in a skillet and season the chicken generously with salt (2 teaspoons salt) and pepper (½ teaspoon pepper).
Brown the chicken for 3 minutes per side. Remove and set aside.
Heat the remaining 2 tablespoons of butter in the Instant Pot on the normal sauté setting. Add the onions and garlic and sauté until soft, about 2-3 minutes.
Add the flour and paprika and stir to coat the onions. Continue stirring to keep the paprika from burning and sticking to the pan. Cook for 1 minute.
Add the tomatoes, chicken stock, fish sauce, salt and pepper. Stir and bring to a simmer.
Add the chicken back to the pot and pressure cook on high for 12 minutes.
Let the pressure release naturally for 10 minutes, then use the manual release for any remaining pressure.
Stir in the sour cream and the lemon juice and season with additional salt to taste if necessary. Serve over egg noodles or rice.
It is very important to use fresh paprika in this recipe. I also highly recommend Hungarian paprika for the best deep flavor. Look for sweet Hungarian paprika if you prefer a less spicy dish. Regular paprika can be substituted in a pinch. While not quite as flavorful, the dish still comes out amazing.
I highly recommend using chicken stock, not chicken broth. Chicken stock adds a richness to the dish. Also, note the recipe calls for unsalted. If you buy a stock that has sodium, make sure to taste before adding additional salt.
Do not add the sour cream until the end. Simmering the sour cream may cause the sauce to curdle and get lumpy. Stir it in at the very end after the heat is off for a perfectly creamy texture.
I use the 6 quart 9-in-1 Instant Pot for this recipe. The instructions should be the same using the larger size.