Cut four large pieces of aluminum foil. You will use one piece to cook each salmon fillet with its corresponding vegetables.
2.
Place a few asparagus spears (after cutting off the hardest part of the stalk) on each piece of foil. If you like, you can cut the asparagus into pieces or leave the spears whole.
3.
Add the mushrooms, the leek, the salmon and, on top, a splash of extra-virgin olive oil, salt, vinegar, pepper and rosemary.
4.
Wrap the ingredients in the aluminum foil so that they are completely sealed and bake the packets at 356ºF for about 30 minutes.