1. Heat the oil in a saucepan and sauté the onion and garlic for five minutes until softened. Add balsamic vinegar, yeast extract or miso paste, tomato purée and mushrooms and cook for a further eight minutes.
2. Sprinkle the flour on top and stir to incorporate. Add stock and bring to a boil, then reduce heat and simmer for about five minutes until you have a gravy-like mixture. Remove from heat, stir in the beans and cool completely.
3. Preheat the oven to 200ºC fan/ 220ºC/425ºF/gas 7.
4. Divide the filling into four individual pie dishes. Brush the edges of the dishes with a little aquafaba or milk.
5. Slice both pastry sheets in half and use a half to top each pie dish, crimping the edges to seal and scoring the tops with a sharp knife. Brush the tops with some more aquafaba or milk and bake for 30 minutes until puffed and golden on top. Serve immediately.
Great British Vegan by Aimee Ryan, is published by White Lion Publishing on 5 January, priced £20. To buy at a discount, visit the Saga Bookshop.
Visit our vegan recipes section for more delicious meat-free meal ideas