Pour the fish stock and sliced chilli into a saucepan and bring to the boil, then keep on a low simmer.
In a separate pan, melt half the butter over a medium heat. Stir in the onions/shallot and sweat gently for up to 5 minutes until soft but not coloured, stirring occasionally. Turn the heat up and stir the rice into the onions until completely coated in the butter, stir continuously until the rice is shiny and the edges of the grain start to look transparent – approx. 3 minutes.
Pour in the wine and simmer until totally evaporated. Add the stock, a ladleful at a time, stirring with each addition until absorbed. Continue adding stock a ladleful at a time and stirring the rice over a medium/low heat, until the rice is cooked al dente - this will take about 15 minutes (with a slightly firm, starchy bite in the middle).
Add the prawns and peas after 11 minutes.
Once cooked, the risotto should be creamy and slightly soupy. Stir through the chopped chilli, lemon juice and remaining butter. Let the risotto rest for a few mins, then serve, topped with the smoked salmon, lemon zest and freshly ground black pepper.