Bring the stock to the boil in a medium saucepan. Reduce the heat to maintain a simmer.
Meanwhile, melt the margarine in a large heavy saucepan over medium heat. Sauté the onion until barely soft, about 3 minutes. Add the rice and 6 strips of red capsicum and sauté until the rice is opaque, about 2 minutes. Add the wine and stir until it is absorbed, about 3 minutes. Gradually add 2 1/2 cups stock, about 1/2 cup at a time, stirring until the liquid is absorbed after each addition – about 10 minutes in total.
Stir in the asparagus, the remaining capsicum, and 1/2 cup stock. Cook, stirring constantly, until the stock is absorbed. Repeat with the zucchini, peas and another 1/2 cup stock.
Continue cooking – stirring constantly and adding the remaining stock 1/2 cup at a time – about 15 minutes more, or until the rice is creamy and tender but firm. Remove from the heat and stir in the Parmesan cheese and pepper. Serve hot.
Risotto isn't difficult, but it does need constant attention. Stirring the rice continuously, while adding the stock gradually, helps the rice absorb the hot stock. This causes the rice grains to release starch, yielding a creamy dish.