A delicious, colourful appetizer designed to pleasantly surprise both the palate and the eye, perfect for impressing your guests and making the most ordinary of meals something special and well-presented. The filling of these little canapés is made from red onions, tender and pleasantly 'sweet-and-sour'. Perfect as a starter or as part of a buffet. Serve while still warm or at room temperature, whichever you prefer. And don't forget to open a good bottle of sparkling wine!
Peel the onions and cut them into reasonably thick slices. Add a little oil to a frying pan and sweat the onions for about twenty minutes . When they are nicely softened add the sugar, salt and balsamic vinegar, then deglaze. Remove from the heat. Roll out the pastry and cut out some circles of about 5 cm in diameter using either a pastry cutter or a small glass. Arrange the pastry circles on an oven tray lined with baking parchment. Sprinkle each circle with the parmesan. Place a slice of onion on top of the parmesan. Finish by pinching and raising up the dough around the onion, leaving it slightly raised. Brush with the beaten egg yolk and bake for 20 minutes at 180°C. Top with some more shavings of parmesan and a few marjoram leaves, then serve.