Preheat the oven to 190°C. Line a baking sheet with parchment paper.
Drain the peppers and pat dry on paper towels. Slice the peppers into very thin strips.
Put the puff pastry onto a large chopping board. Roll it out onto its own wrapping paper. Cut the sheet into about 5-6 cm squares, then score them with a sharp knife 5mm from the edge. Place them on the baking try, leaving some space between them.
Put a drop of pesto in the middle of each square, spreading out the paste within the scored line. Add some roasted pepper strips.
Bake for about 10-15 minutes until the puff pastry is golden. Transfer them to a wire rack to cool slightly or completely.