Steam the sweet potatoes for about 20 minutes: they should become very soft. Let them cool, peel them, and mash the flesh. Add the finely chopped onion, along with all the spices, the chopped parsley, the mustard, the breadcrumbs, salt, and pepper.
Preheat the oven to 185°C. Cut the puff pastry into 2 rectangles of 11 cm width; do not remove the baking paper. Arrange half of the mixture in the center of each rectangle, in the shape of a long sausage. Fold the sides of the dough over the sausage and press the edges to seal them; trim the ends evenly. Cut the rounded side of the sausage rolls about every 2 cm with scissors. Turn every 2 pieces once to the other side, so they are staggered. Turn them one by one, without loosening them, with the filling side facing up. Brush them with beaten egg and then sprinkle with sesame and parmigiano.
Mix the meat, chopped parsley, chopped onion, satay spices, mustard, salt, and pepper. Follow all the steps of the veggie version, but without sesame and parmigiano.
Bake everything for 25 minutes until golden brown in the oven and serve warm, with pickles, onions, and mustard.
Tips
Puff pastry can be cut and processed more easily if it is very cold, so remove the sheets from the fridge one by one.