Method
First, light the barbecue and get it ready for cooking (if you’re using charcoal, our handy guide to getting the best from a charcoal BBQ has some great tips). Next, put the soft butter into a mixing bowl and crush in the garlic clove, then add the lemon zest and a pinch each of salt and pepper. Beat it all together gently until well combined, then set aside. Roughly chop the seaweed, then mix it through the butter. Season well with salt and pepper and set aside. Using a sharp knife, cut three scores in to the top of the brill (don’t cut too deep), then rub a little olive oil over both sides of the fish and season it all over with salt and pepper to your taste. When the barbecue is ready, put the brill on the grill and cook for about 6 minutes, turning regularly, until the skin is nicely charred and the flesh opaque – to check, look at the fleshiest part of the fish, just behind the gills.
Have a large sheet of foil ready (large enough to wrap the fish comfortably). Carefully lift the brill off the grill and on to the foil, then spread it all over with the garlic butter. Pull the foil up to form a parcel round the fish and seal the edges tightly, then put it back on the grill for about 10 minutes or until the flesh flakes easily away from the bone. Serve with your favourite grilled veg – or why not try these easy, tasty potato skewers