Arrange the ham and a pile of the salad leaves on 4 plates. Generously rub the base of a large non-stick frying pan with the block of butter and cut the remainder into small pieces.
Set the pan over a high heat and, as soon as the butter starts to smoke, add the scallops and sear for 2 minutes on each side, seasoning them with a little salt and pepper as they cook. Arrange the scallops on top of the ham.
For the dressing, remove the pan from the heat, add the sherry vinegar and stir to scrape up any residue from the bottom of the pan. Return the pan to the heat, add a tablespoon of water and whisk in the butter, a few pieces at a time, then add the parsley and season with a little salt and pepper. Spoon the dressing over the leaves and serve.
Recipe by George Hughes Fishmongers at https://www.georgehughesfishmonger.com/fish-seafood-valentines-menu-for-two/