Whizz some gluten free bread in a food processor to make the breadcrumbs.
To make the tzatziki, squeeze and discard the juice from the cucumber, then mix into the lactose free cream with the chopped mint, lemon juice and a little salt.
Work the gluten free breadcrumbs into the lamb with the spices and seasoning, then shape into 4 burgers. Brush with a little oil and fry or barbecue for about 5 mins each side until cooked all the way through. Serve in the gluten free buns (toasted if you like) with the tzatziki, tomatoes, onion and a few mint leaves.