The menu above the counter shows which options are gluten free. You can get it in a bowl instead of a burrito/taco. Around €7 for most options
If you tell your server you are coeliac, they immediately change their gloves and explain what you can have. I get either the salad or the burrito bowl. They are really filling and delicious, one of my favourite places to go! Allergen information is usually on the wall somewhere while you're queueing. Great if you're like me and hate asking!
While not explicitly mentioned on the menu there are tacos (the corn hard shell ones), salads and burritos in a bowl which can be gotten gluten free. All dishes are made to order like a sandwich bar and staff are very friendly and will happily tell you what is suitable. Very tasty and almost all of the filings are suitable, just the tortillas as a base are not suitable last time I was there.