Heat the oil in a pressure cooker. Stir in the onions and sweat gently for 8-10 mins until soft but not coloured, stirring occasionally. Stir the rice into the onions until completely coated in the oil, then stir continuously until the rice is shiny and the edges of the grain start to look transparent.
Pour in the wine and simmer until totally evaporated. Pour in the stock, close the lid and bring up to high pressure. Cook for 5 mins, then release the pressure quickly. Place the pan back on a low heat and stir through the prawns and peas. Simmer gently until the prawns change colour. The risotto should be creamy and slightly soupy.
Stir through the chilli, lemon juice and remaining olive oil. Let the risotto rest for a few mins, then serve, scattering over the lemon zest.