Steak and Mushroom Pie w/ Guinness

2 tbsp oil
1 kg stewing steak, cut into cubes
250g flat mushrooms, quartered
1 tbsp coarse-grained mustard
1 onion
2 tbsp plain flour
1 stubby Guinness beer
500ml beef stock
salt and pepper to taste
sheet of frozen puff pastry
beaten egg to glaze

Directions
Heat oil in frying pan, add beef, a few pieces at a time, and fry until evenly browned.

Drain and put aside. Fry onion until softened, add mushrooms and cook a further 3 minutes. Return meat to the pan, sprinkle flour and mix well. Add Guinness and stock, mustard and seasoning. Cover and cook in a casserole dish at 180C for 1 1/2 hours.

Spoon the beef mixture into a 1 1/2-litre pie dish and cool. Keep extra sauce. Place dish on top of pastry and trim. Cut trimmings into thin strips.

Brush edge of dish with water and place strips on dish edge. Brush with water. Place lid in position and press edges together, trim pastry if needed. Brush pie with egg.

Cook at 200C for 55 minutes, cover with foil if over-browning. Reheat extra sauce and serve with pie.