Fry the onion and garlic together in a little oil for 5 minutes then add the rice and cook for another 3 minutes. Add the peas and lemon juice/zest.
Gradually add the vegetable stock and milk, stir each time and allow rice to absorb all liquid before adding more. Repeat this until all of the stock has been absorbed. The risotto rice should be soft and oozy.
Poke flakes of the fish into the hot risotto and sprinkle in the salad leaves, take off the heat and allow to stand for 5 minutes.