For filling, cook spinach according to package directions. Drain well, pressing out excess liquid. In a skillet cook the green onions in butter or margarine until tender but not brown. Stir in bread crumbs and egg yolk, then stir in spinach.
In a large skillet bring 2 cups water just to boiling. Carefully add fish. Return just to boiling, then reduce heat. Cover and simmer gently for 2 minutes (fish will not be done). Remove fish from water. Pat fish dry with paper towels.
On a floured surface roll pastry into a rectangle about 4 inches longer than length of a fillet. Lay fillets side by side; measure width. Roll pastry to twice the width plus 2 inches.
To assemble, transfer to an ungreased 15 x 10 x 1-inch baking pan. On half of the rectangle, spread half of the filling to within 1 inch of edges. Top with fish, then with remaining filling. Combine egg and water, then brush some onto pastry edges. Bring pastry over fish. Seal edges with the tines of a fork. Brush top with remaining egg mixture. Bake in a 400 degree F oven for 20 to 25 minutes or until golden. Serve with sauce. Makes 6 servings.
In a small mixing bowl combine cucumber, yogurt, mayonnaise or salad dressing, milk, and dried dillweed. Stir until well blended. If desired, cover and chill to blend the flavors before serving. Makes 3/4 cup.
Blender Hollandaise Sauce
In a saucepan heat butter or margarine, lemon juice, and ground red pepper until butter is melted and the mixture is almost boiling. Remove from heat. Place egg yolks in a blender container. Cover and blend for 5 seconds. Through the opening in the lid or with lid ajar, and with blender on high speed, gradually add butter mixture. Blend about 30 seconds more or until thick and fluffy, stopping to scrape sides as needed. Serve immediately. Makes 1 cup.