A fine place for a cheap outdoor lunch is Paninoteka. While the Panini are quite tasty, the best part about eating here is the prime people watching seats you can get just off the Cobblers' Bridge. Enjoy the cheap and filling sandiwches, nurse a beer or a Cockta, and enjoy!
Favorite Dish: I had a panino with prosciutto, cheese, and olives. Very nice.
Although it is not a traditional Slovene eatery, to find a great sandwich head to Paninoteka. It is in the heart of the old town right along the river at: (Jurèièev trg 3, Ljubljana Telefon: +386 (0)1 425 00 55).
If the weather is good, the ambiance is excellent, it shares an outdoor area with a bar across the way. It has a wide range of alcoholic and non-alcoholic drinks and a vast menu of sandwiches. They make their wraps from scratch (I had the grilled chicken one and it was great). It is a chill place and the prices aren't bad either.
Favorite Dish: The grilled chicken wrap, it is more expensive than the others, but worth it.