Created by ImPat on September 30, 2017
Step 1: Preheat oven to 220C/200C fan forced.
Step 2: Melt the butter in a medium (20cm top measurement) ovenproof frying pan over moderate heat and add the leek, celery and carrot and cook and stir for 3 minutes or until golden brown.
Step 3: Add flour and cook and stir for 1 minute or until mixture thickens and then gradually whisk in the boiling water, crumbled stock cube and cream and cook and stir for 3 minutes or until the sauce boils and thickens and then add the mustard, zest, fish, parsley and dill and stir to combine.
Step 4: Brush the frying pan edge with a little egg and top with the pastry sheet, trim edges to fit and then brush top with a little more egg and plan the pan on an oven tray and bake for 25 minutes or until pastry is puffed and fish cooked (flakes easily when tested with a fork).
Step 5: Serve with lemon wedges.