Peel the asparagus and chop into pieces. Bring the peel to the boil in 1 l of water, simmer for approx. 10 mins. Drain the peel, retain the cooking water. Add the stock to the liquid, bring to the boil. Add the chopped asparagus, simmer for approx. 5 mins. Drain the asparagus, retain the cooking water.
Heat the oil in a pan, sauté the onion. Add the rice and sauté until translucent, stirring constantly. Pour in the wine and reduce completely. Stirring frequently, add the retained cooking water a little at a time so that the rice is always just covered with liquid, simmer for approx. 15 mins. Mix in the pieces of asparagus, then season.
Plate up the risotto, garnish with the feta, hazelnuts and parsley.