Brush the salmon with the oil. Sprinkle with the dill. Wrap two layers of foil around the salmon. Seal and fold the ends over 3 or 4 times.
Put the salmon in the upper dishwasher rack. Turn to the normal cycle, which should run for about 80 minutes. Cook til a meat thermometer registers at least 160 degrees. Mix the mayonnaise and lemon juice in a small bowl.Serve the salmon hot or at groom temperature with the lemon sauce.
You may also substitute cod, trout or orange roughy steaks instead of salmon.