Finely chop all vegetables.
Heat the oil in frying pan and gently sauté the onion and celery for 5 minutes. Add the garlic and the herbs, then stir for a minute.
Add the other veggies (except the peas) and, under a lid and over low heat, sauté for 5 minutes.
Add the water and stock powder, stir, then put a lid on again and gently cook for 10-15 minutes, until the veggies are tender.
Add the peas, then sprinkle the top with corn flour and reduce the sauce until you get a thick gravy.
Let it cool. (This can be made well ahead and kept in the fridge)
Preheat the oven to 180°C.Unroll the pastries and cut out 4 squares per sheet.
Pile some filling in the middle of each square.
Dampen the edges of the pastry with water or plant-based milk, then fold across diagonally.
Pinch and twist the edges together to form a curved pattern.
Place them on a baking tray, lined with parchment paper.
Brush them with some plant-based milk, then bake in the oven for about 25-30 minutes or until golden brown.
Serve warm or at room temperature.