In a large pan, heat the oil on medium heat and cook the sausage on both sides (4-5 minutes on each side). When cooked, remove from the pan and reserve. Alternatively grill the sausage on a braai or in the oven. (You can also skip this step and stuff the pastry with the raw sausage meat, removed from the casing).
In a pan, heat the oil for the caramelised onions to a medium-low heat. Add the onions, a pinch of salt and the sugar. Allow to cook for 15-20 minutes, stirring occasionally until the onions are soft and caramelised.
Finely chop the mushrooms and sautee in the oil over medium high heat until lightly browned.
On a lightly floured surface, roll the puff pastry slightly and cut into 11cmx13cm rectangles. Place them in the fridge until needed.
Working on one rectangle at a time cut approximately 1 cm strips along the edge of the rectangle, leaving roughly 3 cm in the centre for the filling. See image guide. Cut out the greyed out portion and tuck in the pointed ends to make a ‘boat’ for the filling (see video below for guidance).
Add some of the caramelised onion, a teaspoon of the mushrooms and a piece of the sausage in the centre.
Cross one strip over the filling from one end, then proceed to another strip from the other and carry on to form a plaited effect. Tuck the ends and trim off any extra strips. Place in the fridge until ready to bake. Alternatively freeze and bake from frozen when needed.
Pre-heat the oven to 200℃ and line a baking tray with baking paper.
Brush the plait with the egg wash and sprinkle on the sesame seeds.
Bake for 18-22 minutes or until the puff pastry is golden brown all over.
Remove the plaits from the oven and allow to cool on a cooling rack. Enjoy warm or cold with a spicy dip or side salad.