Toast celery seeds in a dry large frypan over low heat for 1-2 minutes, until fragrant. Transfer to a bowl and set aside to cool.

Heat vegetable oil in same pan over low heat. Cook onion and garlic, stirring occasionally, for 8-10 minutes until lightly caramelised. Stir in toasted celery seeds and herbs, then transfer to a bowl and set aside to cool.

Wipe out pan, return to medium-high heat and melt the butter. Add apple and cook, tossing gently, for 2 minutes. Add sugar and cook, stirring constantly, for 5 minutes or until lightly caramelised. Add vinegar, scraping bottom of pan with a spoon. Set aside to cool.

Preheat oven to 200°C/180°C fanforced. Line two large baking trays with baking paper.

Place mince, breadcrumbs, salt, apple mixture and onion mixture in a large bowl. Using your hands, mix for 3-5 minutes until all elements are evenly distributed.

Cut each pastry sheet in half crossways, then divide sausage mixture evenly between the four pieces, forming a thick line along one long side. Lightly brush egg along the top edge of pastry. Roll pastry up from the bottom of each roll, away from yourself, folding it over the sausage mixture. Seal roll on the eggwashed edge so the seam is underneath the meat. Brush top and sides with eggwash, sprinkle with sesame seeds and lightly pierce along the top with a fork. Halve each roll, then transfer to prepared trays. Bake, swapping trays halfway during baking, for 35-40 minutes until cooked and golden.

Rest for 10 minutes, then serve with tomato chilli jam alongside (see note).