Roll out a rectangle of puff pastry (for instance 20cm x 10cm).

Spread some black olive paste or tapenade over the entire surface, leaving a 1cm border along the end (across the 20cm length).

Dab some egg yolk along the border and then roll up neatly. Dab with some egg yolk across the top and sprinkle with sesame seeds. Refrigerate till cold and then cut into 1cm pieces.

Bake in a 180C oven till nicely browned (around 15 minutes).