Soften the onion in your pressure cooker, add salt and pepper.
When the onions are softened add the rice and lightly toast it to release the starch.
When you add the Arborio rice to the onions it will turn it from white to translucent as it absorbs the oil, then in about a minute back to white. Wait until just a couple of grains look golden and your rice is toasted!
Add a swig of white wine and stir until it has evaporated. Add the broth, stir, and then close and lock the lid.
Place the pressure cooker on a burner and turn the heat to High. When it reaches pressure, lower the flame to low heat and cook for 7 minutes for al dente risotto or 9 for well done on High (11 minutes or 14 minutes on Low).
Near the end of the cooking time, take the whole cooker off the flame and swirl it around to feel if it is still has a lot of liquid inside. It should feel a little dense but not soupy.
When the time is up, open the pressure cooker with the quick-release cold water method by bringing it to the sink, giving it a little jiggle to settle the contents inside, and running cold water on the top until the pressure subsides and you can open the top. DO NOT pour the water into the pressure valve, the water should only make contact with the stainless steel part of the lid.
If the risotto inside is a little wet, it is perfect. The risotto will absorb the liquid by the time you serve it to your guests. If it is still very wet, put the open pressure cooker back on a medium flame and simmer to the right consistency.