Instructions

1. Putting chicken in buttermilk is a wonderful way to quickly tenderise it and make the flesh much more succulent. If you had the time you could leave it in the buttermilk overnight, but 15 minutes at room temperature really does make a difference.
2. Cut each chicken fillet in half into 2 thin escalopes. Place on a chopping board, put a piece of non-stick parchment paper on top of each one and quickly flatten out with a rolling pin to about 1cm (½in) thick. Place the buttermilk and salt in a bowl and add the chicken. Set aside at room temperature for at least 15 minutes to allow the buttermilk to tenderise the chicken, or place in the fridge overnight if you have the time.
3. Meanwhile, to make the celeriac slaw, peel the celeriac and then cut into julienne on a mandolin. Whisk the parsley, chives, buttermilk, maple syrup, mustard and vinegar into the mayonnaise and then fold in the celeriac. Season to taste.
4. Preheat the grill to high. Melt the butter in a small pan or in the microwave, then tip into a bowl. Add the breadcrumbs and Parmesan and season to taste, then mix well to combine. Remove the chicken from the buttermilk marinade, gently shaking off any excess. Place on a greased baking sheet and top with the breadcrumb mixture. Grill for 4–5 minutes, until the chicken is cooked through and the crumbs are golden.
5. Arrange the celeriac slaw on the chargrilled sourdough on warmed plates. Top with the crispy buttermilk chicken and scatter over the chives. Serve at once with small dishes of tomato or chilli relish for dipping.