What is the fine-grained topic of the following text: That Tsujita has expanded should come as no surprise to anyone who has spent time waiting outside the original shop at lunchtime, when long lines often snake down the street as the usual crowd waits for a table at which to consume tsukemen, the dip ramen in which the restaurant has specialized since its opening in 2011, which is served only at lunch. Only return the topic.
Tsujita restaurant's expansion and its specialty in tsukemen dip ramen.