01 -
Preheat oven to 180°C (350°F).
02 -
Heat a small oven-proof pan over medium-low heat and melt the butter completely.
03 -
Add the halved onion to the pan and cook until slightly golden on both sides, approximately 3 minutes per side.
04 -
Pour the honey, balsamic vinegar glaze, salt, and black pepper over the onion and around the pan.
05 -
Remove the pan from heat. Cover with the puff pastry sheet, trimming excess edges and creating a slight pleat by pressing sides together. Seal edges with a fork.
06 -
Whisk together the egg and water in a small bowl. Brush this mixture evenly over the top of the puff pastry.
07 -
Bake in the preheated oven for approximately 15 minutes, or until the pastry becomes golden brown.
08 -
Remove from the oven and carefully invert the tatin onto a serving plate. Garnish with sesame seeds, sliced scallions, and red pepper flakes before serving.