Cut the bell pepper in half, remove seeds, and chop coarsely. Defrost the frozen puff pastry sheets.

Grease an ice cube tray with a little salad oil and dust with flour. Lay two puff pastry sheets over the tray, slightly overlapping, and press into the tray. Add ketchup, bell pepper, corn, and mozzarella cheese into each section. Cover with the remaining puff pastry sheet.

Press the surface gently to smooth it out, seal the edges, and trim excess pastry. Place trimmed pastry on top and smooth it out. Chill in the freezer for 2 hours.

Remove from the ice cube tray and cut into individual pieces along the tray's divisions. Place on a baking sheet lined with parchment paper.