Another fun and yummy place to eat in St. John's is Quintana's de la Plaza in Churchill Square. It's a Mexican restaurant and the food is fabulous!
This restaurant is very accommodating to gluten-free customers and their menu indicates to tell the server if you require a gluten free dinner. I have never had any problems with requesting gluten free and I have never had cross contamination issues. They have a good size menu and I typically substitute the flour tortilla in a dish with a corn one.
My favourite is the Habanero Burrito with chicken on a corn tortilla. Because the corn tortillas are smaller, I usually get 2 as opposed to the larger flour one. If you are not a Mexican fan - they have some Canadian Fare such as Stirfrys and salads - just be sure to tell the server you need it to be gluten free!
The pricing is fairly average for a St. John's restaurant - but because it's small, I'd recommend reservations for a weekend!
You can check out their website and menu here