Heat your oven to 200°C / 400°F / Gas mark 6.
Put the porcini mushrooms in a small bowl and cover with boiling water. Allow to stand for 20 minutes.
10 g Porcini mushrooms, 100 ml Boiling water
Put the oil and onions in a sauce pan / frying pan and sweat over a medium-high heat for 5 minutes.
1 tbsp Mild olive oil / sunflower oil, 1 Medium Onion, chopped
Add the mushrooms, along with some salt and pepper. Fry for 10 minutes, stirring regularly.
250 g Mushrooms, sliced
Add the garlic and cook for a further 2 minutes.
2 each Garlic cloves, minced
Stir in the dijon mustard, tomato puree, vegetable bouillion powder and hot water.
½ tsp Vegan dijon mustard, ½ tsp Tomato puree, ½ tsp Vegetable bouillion powder, 200 ml Boiling water
Strain the porcini mushrooms over a bowl / jug into a sieve. Reserve the mushroom liquid.
Chop the porcini mushrooms a little and add to the pan along with 50ml of the mushroom liquid (avoiding the sediment at the bottom).
Stir in the breadcrumbs and transfer the mixture to a food processor and blitz to your desired consistency. I like it mostly smooth with small pieces of chewy mushroom throughout.
100 g Bread crumbs
Lay the pastry flat on a work surface and cut into three equal pieces.
375 g 1 pack, ready rolled, vegan puff pastry
Turn each piece of pastry so that shorter edges are to the left and right and the longer edges are to the top and bottom.
Put the sausage mixture into a piping bag and pipe down the length of each piece of pastry on the side that is closest to you (the bottom). Keep the mixture to that side in a straight line (it shouldn't spread more than ⅓ of the way towards the top of the pastry, this will allow you enough pastry to properly roll it up).
Brush down the length of each piece of pastry on the top edge with the unsweetened plant milk. This will act as a glue when you roll the sausage rolls up.
Carefully lift the pastry closest to you and gently but surely roll over until you have formed a large sausage roll.
Chop off the ends so they are neat, cut each sausage roll in half and then half again and transfer to a baking sheet, allowing a little space between each sausage roll for the pastry to puff up.
Brush each sausage roll with unsweetened plant milk and scatter sesame seeds over the top of each roll.
Bake at the top of the over for 25 minutes or until golden brown. Serve.