Heat oil in a large pan and brown steak pieces in batches until golden-brown.
Sauté onion, mushrooms, shallots, and carrots in the same pan for 2–3 minutes.
Stir in thyme, bay leaves, and tomato purée.
Deglaze the pan with ale, scraping up the browned bits from the bottom.
Add beef and hot stock, boil, then simmer covered for 1.5 hours until beef is tender.
Cool the filling completely.
Preheat oven to 220°C.
Transfer filling to a 23cm round ovenproof dish.
Roll pastry to 1cm thickness and cut a circle slightly larger than the dish.
Wet the dish rim, place pastry over the top, and press edges to seal.
Brush with beaten egg and bake for 20–30 minutes until golden-brown.
Soak peas in water with bicarbonate of soda for at least 4 hours.
Drain, rinse, and simmer peas in water for 1.5–2 hours.
Beat in butter and salt once peas are soft and mushy.
Serve slices of pie with a side of mushy peas.