Method
Well before you plan to cook, light your barbecue so that it has time to come up to temperature (see our handy guide to getting the most from a charcoal barbecue to learn more). That said, don’t put the fish on the very hottest part of the grill - it’s best to place it over a medium-hot area, to avoid burning the skin before the middle has a chance to cook. While you wait for the barbecue, make the marinade; put all the marinade ingredients in a large shallow dish (large enough to hold both fish steaks comfortably) and whisk together to combine. Season to taste with salt and pepper, then put the fish into the dish and turn until well coated in the marinade. Cover and leave in the fridge until the barbecue is ready. Make the yoghurt sauce by mixing the cucumber, mint and a generous pinch of salt into the yoghurt, then cover and refrigerate until needed. When the barbecue is ready, take the fish steaks out of their dish and put them on the grill for 4–5 minutes, then turn them and cook for a further five minutes, brushing with the leftover marinade from time to time, until the flesh is opaque, flakes easily and is thoroughly cooked through. Take the steaks off the barbecue and wrap loosely in foil, then allow them to rest for a few minutes while you warm the flatbreads on the grill. Serve the steaks by flaking the fish away from the bone and into a warm flatbread, then topping with the yoghurt sauce and folding the whole lot up to eat.