Peel potatoes and cut into (4 mm or 0.2 inch) slices. Wash zucchini and cut into slices.
Take two sheets of aluminium and coat with anti-stick cooking spray (like Pam).
Place the potato slices leaving room between each for a zucchini slice. Season to taste.
Place the salmon filets on top of the layer of potatoes and zucchinis and then season again.
Add a line of sorrel puree on each filet.
Close the papillotes and cook on medium heat for approximately 20 minutes on the barbecue.
Note: You can find the sorrel in fine grocery stores (Tousain brand).
Variation: You can replace the sorrel with a dill puree (frozen) or with pesto.