Heat olive oil in a large pan and sauté onion till soft. Add Arborio rice and continue to sauté for two more minutes. Add half of the vegetable stock and cover and cook for two to three minutes.
Add mushrooms and zucchini and mix well. Add the remaining vegetable stock, white wine, salt and crushed peppercorns; mix well and continue to cover and cook till almost done.
Add broccoli, asparagus, two tablespoons Parmesan cheese and cook for two to three minutes.
Sprinkle the remaining Parmesan cheese and serve hot.