Before you start, preheat oven to 220°C (or 200°C fan bake).
Prep onion and apple. Heat oil in a medium fry-pan on medium-high heat. Cook onion with salt for 3-4 minutes, until starting to soften. Add to a large bowl with apple, pork and breadcrumbs. Mix well to combine.
Cut pastry in half lengthways. Divide filling into two and shape into long sausages along centre of the pastry. Roll up pastry to form two long sausage rolls. Cut each roll into 4 even-sized pieces and place on a lined oven tray, seam side down.
Whisk egg, then brush over sausage rolls and sprinkle with sesame seeds. Bake for 18-22 minutes, or until pastry is puffed and golden and pork is cooked through.
Prep beetroot and toss in a large bowl with slaw and yoghurt. Season to taste with salt and pepper.
To finish, prep parsley.
Serve sausage rolls with slaw and tomato sauce on the side. Sprinkle slaw with seeds and parsley.