An onion was a vegetable with a strong odour. When Starkey was forced to huddle with Thorne to be transported from Urlic back to Earth, Starkey asked Thorne if he had been eating "onions, or garlic." (TV: Lost Library of Ukko)
Spinthoz was the universe's biggest onion. The Eleventh Doctor visited it during peeling season, having thought it was a planet. (COMIC: Sticks & Stones)
Geoff Paynter frequented the Burger King at Tottenham Court Road for onion rings. (PROSE: The King of Terror)
Onions were added to vinegar in order to make pickled onions. (TV: World War Three)
Cheese and onion was a flavour of crisps. (PROSE: Citation Needed)
According to the Tenth Doctor, Rassilon had a fondness for onions. (COMIC: The Forgotten)
The Final Appearance of Onion was The Women Who Fell to Earth