I reckon they were charcoal buns. https://www.booths.co.uk/recipe/charcoal-brioche-buns/. But they added to much filters . I want to try a Beetroot one. https://recipes.sainsburys.co.uk/recipes/vegetarian/beetroot-brioche-buns. And a venom burger. https://www.flyguy.net/post/162854428107/meetthe-new-venom-burger-australian-burger-chain Outback Kamado Bar and Grill