Chilidogs

Sonic's favorite food is chilidogs. This was a re-occurring case in the Sonic cartoons and comics that even influenced the games. Starting with Sonic Unleashed (2008), the food was officially his favorite and would make subsequent appearances. 

90s

The origin of Sonic's love of Chilidogs began in Adventures of Sonic the Hedgehog, appearing often in the series. Tails was also a fan.

Sonic the Hedgehog ("Sat Am") also incorporated the element into many of it's episodes. The comics followed suit, though they appeared less frequently as the series continued. 

Sonic Underground immediately picked up the idea again when it aired. It wasn't unusual for Sonic to gulp down chiligdogs in large quantities.

2000s

"Pretty Tasty"

Sonic X was the first cartoon to largely ignore the tradition, possibly because it was the first series not by DiC Entertainment or the first not made under "western" cannon. However there was ONE in the episode "How to Catch a Hedgehog" (it was not called so by name, just seen). It was clearly at least a cameo-reference. 

When food became a large part of Sonic Unleashed, Chilidogs were described as Sonic's favorite. Sonic could also earn different versions of dogs by doing missions.

Again they were shown as Sonic's # 1 food in Sonic and the Black Knight.

2010s

Tails gives Sonic one as a gift in Sonic Generations, and it's shown as a popular food item at Sonic's birthday party. Though somewhat referenced in dialogue, Chilidogs kinda' disappeared.

Luckily Sonic Boom carried on the "Chilidog tradition" and used it in the show. However the writers were originally on the fence about whether they should have.