Rinse fillets and pat dry.
Fold fillets in half and arrange in
large ovenproof dish.
Pour wine and lemon juice over fish. Sprinkle with salt, pepper and
dill. Cover with foil and bake for 10 minutes at 350 degrees.
In a large skillet, melt
margarine and cook mushrooms for 5 minutes.
Remove fish from oven and drain liquid into a
glass measurer. Add water to equal 1 1/2 cups liquid.
Add flour to mushrooms and stir
until smooth. Stir in fish liquid and cream.
Bring to a boil and simmer for 5 minutes,
continuing to stir.
Pour sauce over fish.
Beat egg into potatoes and fill pastry bag. With
a number 6 top, make lattice pattern over fish and around edge. If pastry bag is
unavailable, place small scoops of potatoes around edges and over sauce.
Bake at 350
degrees for 25 minutes or until potatoes are lightly browned.