Fish fingers and custard

The Doctor enjoys fish custard.

Fish custard was a dish enjoyed by the Doctor shortly after his regeneration. Having tried and hated multiple foods from young Amelia Pond's kitchen claiming "New mouth new rules" , the Doctor found frozen fish fingers and custard. He enjoyed them together, dipping the fish fingers into the custard. Amelia took the Doctor's enjoyment of fish custard in stride, which he noted as a sign of her bravery.

When the Doctor rejoined Amy Pond as an adult, he realised it had been "14 years since fish custard." (DW: The Eleventh Hour)

Behind the scenes

• Matt Smith initially claimed it was actually fish fingers and custard he was eating, and that he found it "gorgeous." He later admitted the "fish fingers" were actually breaded cakes.
• Steven Moffat has commented on the phenomenon of Doctor Who fans eating fish custard, and claims that it has "taken over from any other breakfast snack." (CON: Out of Time)

Footnotes

Also, if you are a big Doctor Who fan, you can't be one until you have tried fish custard