Heat up the olive oil in a fry pan and add the finely chopped onion. Fry the onion for 8-10 minutes until lightly golden in colour.
Add the chopped mushrooms to the fry pan and cook for about 8 minutes until soft.
Drain and rinse the lentils and add them to the fry pan together with the smoked paprika, celery seeds, cumin seeds, porcini powder, dried oregano and dried thyme. Mix everything until combined and cook for about 4 minutes.
Now stir in the soy sauce, tomato paste and brown sugar. Cook the mixture for another 2-3 minutes and then turn off the heat.
Preheat the oven to 200°C fan and take the puff pastry sheets out of the freezer.
Once the puff pastry sheets have slightly defrosted and are pliable, cut the pastry sheets in half. You should now have 4 rectangular puff pastry sheets.
Add the mushroom-lentil filling into the middle of each puff pastry rectangle. Then roll the rectangle onto itself so that the filling is in the middle of the puff pastry roll. Cut each roll into 4 equal pieces.
Place the individual sausage rolls onto a baking tray lined with baking paper.
Brush the sausage rolls with soy milk and sprinkle some sesame seeds on top of each roll.
Bake the sausage rolls at 200°C fan for 20-22 until golden brown.
Once baked, let the sausage rolls cool down slightly. Enjoy!