Place the vinegar, sugar and salt in a saucepan and simmer until sugar and salt have dissolved. Remove from heat, add the onions and set aside for 30 minutes.

Meanwhile, heat oven to 200ºC regular bake and line a baking tray.

Cut pastry into 6 even rectangles. Run a blunt knife around the edge of the pastry roughly 2cm from the edge to create a border.

Brush the whisked egg around the border and top with sesame seeds.

Bake for 10-15 minutes or until golden and puffed up.

In a bowl, combine the cream cheese, horseradish and herbs, season with salt and pepper.

Smear the cream cheese filling in the centre of each piece of pastry. Top with smoked salmon slices and pickled red onion. Serve with a green salad.