Halibut with samphire and barbecued new potatoes

By Galton Blackiston From Saturday Kitchen Ingredients For the halibut 2 x 250g/9oz boneless halibut fillets 500g/1lb 2oz unsalted butter 250g/9oz samphire For the new potatoes 500g/1lb 2oz new potatoes, peeled and halved 2 lavender sprigs 12 wet garlic cloves, peeled olive oil knob …