FOR THE PIE FILLING:
3 tablespoons - 
duck fat (or goose fat)
2 medium - 
onions
1lb 10oz  - 
lean braising steak (chuck steak)
   - 
salt and pepper
2 level tablespoons - 
plain flour (all-purpose flour)
1 tablespoon - 
Worcestershire sauce
1 tablespoon - 
tomato purée (concentrated tomato paste)
1 teaspoon - 
whole grain mustard
1 teaspoon - 
dried thyme
½ pint - 
brown ale
FOR THE PIE TOPPING:
6 medium-sized - 
potatoes
1 oz - 
butter
up to ½ cup - 
milk
9 oz - 
tender spring greens
   - 
salt and pepper