Combine all ingredients except the fish and potatoes in a large bowl. Cut sweet potatoes into 1 inch cubes. Toss with other ingredients.
Brush four 12 inch pieces of aluminum foil with a little oil. Place salmon fillet on the foil. Top each fillet with one quarter of the potatoes. Fold foil over fish and seal top and ends.
Place on preheated grill and cook without opening for 25 minutes.