Scale and clean the fish.
Wipe inside and out.
Toss crumbs with steeped soup and mayonnaise.
Add a little dill if you have any and stuff the fish.
Take a large oblong of heavy foil, more than twice as long as the fish and oil the centre.
Arrange fish horizontally on one half of the foil and tuck a few slices lemon into the cavity.
Sprinkle with seasoning salt.
Fold second half of foil over the fish and seal the edges together to make an airtight package.
Bake on a rack over hot coals for about 20 minutes.
Turn package and bake another 15 to 20 minutes or until fish flakes.