Heat oil in a frying pan over medium heat. Add onion and cook, stirring, for 3-4 minutes or until softened. Add garlic, pepper, oregano and paprika. Cook, stirring, for 1 minute or until aromatic. Season with salt.

Add mushrooms to the pan and cook, stirring, for 2-3 minutes or until some of their liquid releases. Stir in the brandy or wine, mustard and sour cream. Crumble in the stock cube and stir to combine. Cook, stirring occasionally, for 6-7 minutes or until the mixture is reduced and very thick (but not catching and burning in the pan). Transfer to a bowl and set aside to cool completely.

Combine mince, mushroom mixture and breadcrumbs in a large bowl. Season with salt. Place in the fridge until required.

Line a baking tray with baking paper. Cut pastry sheets in half. Form a log shape with one-quarter of the mince mixture along 1 long edge of each piece of pastry. Brush the opposite long edges with egg. Use the baking paper to help roll the pastry around filling to enclose, pressing the edge to seal. Place the sausage rolls, seam-side down, on the lined tray. Place in the freezer for 10 minutes to firm up.

Preheat oven to 200C/180C fan forced. Use a small, serrated knife to cut each roll in half, then each smaller roll in half again, separate rolls leaving at least 2cm between each. Brush tops with egg and sprinkle with extra pepper and extra paprika, and some salt. Bake for 25-30 minutes or until golden and cooked through. Serve warm with tomato sauce and extra sour cream.