Matt wants to know how it's possible for British onions to be sold in supermarkets all year round. The answer lies not in our soil, but in a disused aircraft hangar. Is pricey aged steak worth the wait? Jimmy visits a top butcher to find out how aged beef is produced and whether it's possible to mature-age your own steaks at home. Kate is intrigued about what goes into a stuffed olive. In Greece, she discovers that the filling in pimento olives is not just red pepper, but also contains another, surprise ingredient: Food Unwrapped's old friend, seaweed.