Granny used to make this for a lunch now and then.
Sauce:
Choux pastry:
Fry onion and mushroom in butter. Add flour and cook till thickens. Add milk and cook till a thick sauce forms. Add tuna and lemon and cool. Season to taste.
Boil water and butter for pastry.
Stir in dry ingredients and stir until it forms a ball. Cool for 5 minutes.
Beat in 1 3/4 of beaten eggs, saving some for brushing pastry to bake.
Add cheese.
Place spoonfuls around a greased shallow pie dish, pushing them close to the edges. Brush with remaining egg.
Spoon tuna mix into center of pastry and bake for 45 minutes at 370°F.
Pastry should sound hollow earn cooked, and no bubbles remain visible on surface.
Garnish with tomato wedges and parsley.
Serve with a green salad.