Apples, potatoes, and onions all taste the same when eaten with your nose plugged.
As a child we had a science class in which we were blindfolded, had our noses plugged, and given an apple or onion to eat – we were not told which of the two we would be given. Not one person was able to state which was which. This shows the incredibly important part that the nose plays in the sense of taste. The fact that the three items have a similar consistency makes it virtually impossible to tell them apart without the sense of smell. If you try this, I should warn you: once you unblock your nose, you can tell what you have just eaten.