If a piece of meat is too thick to cook through without drying out, this French technique will save the day – and you don’t need to be Zorro to pull it off. Slice the meat most of the way through, horizontally, then unfold – as if opening a book – to make a butterfly shape. The heat can now reach more of the meat, and it’s easier to check how cooked it is. You could also put a stuffing inside and seal with string before roasting – Chicken Kiev is made in this way.