Last night I ate some Buffalo Mozzerella from Morrisons that was much much better than I was expecting. Tasting it was very nearly as good as being in Italy! (I admit to having very low expectations of UK supermarket food, but that's another issue.)
Do you have any particular food items from supermarkets (presumably favourite items) that turned out to taste really very much better than you were expecting?
Pls give the exact items, a comment why and which Supermarket, even if the item has since become unavailable or very hard to find (it does happen!)
If you're not a foodie, you'd perhaps best ignore this thread! 
Sainsbury Taste the Difference Dijon Mustard, I'd add that to this list too.