18 slices Carmarthen ham or any good quality air-dried ham
1 Perl Wen (a Welsh cow's milk cheese) or 2 balls buffalo mozzarella, drained and each cut into 6 wedges
toasted sourdough bread, to serve, optional
Cut leeks in half lengthways, wash thoroughly, then thinly slice. Heat olive oil in a non-stick pan and add the leeks. Cook quickly over a med-high heat, stirring regularly until the leeks are tender with a little bite and still vibrant in colour, about 5-10 mins.
Remove from the pan and allow to cool to room temperature. Fold in the grain mustard (1 tbsp at a time, to your taste) and chopped chives, and season with a little sea salt. The leeks can be made up to 3 hours ahead and left, covered, at room temperature.
Serve the leek vinaigrette in a small heap on each plate. Then add the ham and 1-2 wedges of cheese. Serve with toasted sourdough bread, if you like.