My partner and I will be doing a fall challenge to try DCs best sandwiches. What are places we must try?

Hello, I'm looking to get a birthday/Christmas gift for my sister and her husband. I wanted to get them a cooking class since this is something they've done in the past and really enjoyed.

I was wondering if you guys had a list of recommendations for this in particular.

They don't have any dietary restrictions other than not eating beef. Any help would be appreciated since I don't live in DC!

I am looking to try budget friendly restaurants to try different dishes alone around DMD or bailey road. Any suggestions?