In a large frying pan add the rapeseed oil, once warm add the chopped mushrooms and thyme, cook on medium heat for 20” stirring every now and then to make sure they don’t burn. Set aside.
In a large mixing bowl combine the cooked mushrooms with the vegan mince meat, chopped walnuts, sage and onion stuffing, salt and oat milk, mix well.
Unroll the pastry, as it’s rectangular, keep the longest side horizontal, now cut it in half vertically.
Place the filling on the right side of one of your 2 halves leaving a 2 cm edge on your right, now fold the left part of your pastry on top of the filling, make it quite tight, with a fork pinch the pastry to seal the sausage roll and cut the excess with the knife. Do the same process with the other half of your pastry, then cut both into 6 small sausage rolls, so that you’ll achieve 12 sausage rolls in total.
With a knife make a small cut on top of each roll, brush them with milk evenly and sprinkle the nigella seeds.
Place the sausage rolls evenly spread out on a baking tray with parchment paper and bake for 25” until golden.