For the dish
Serve puree onto the plate. At random points of the plate, place the leeks and pancetta. Finish with the sauce, green apple, oil and rosemary.
For the pancetta
Marinate the pancetta in the brine for 24 hours.
Remove pancetta and dry very well.
Mix butter, honey, beer and olive oil and spread onto the pancetta.
Wrap tightly in parchment paper and bake in the over at 120°C for 5 hours.
Place in a baking dish and allow to cool at room temperature.
Cover with a piece of baking paper, place a second baking dish on top and weigh down with something heavy (e.g. tins).
Store in the fridge for 12 hours.
Cut the pancetta into 4 same size, rectangular pieces.
Place an non-stick frying pan over medium heat and sauté, skin-side down, until it forms a crispy crust and the pancetta heats through.
For the braised leeks
Place a pot over medium heat and sauté the leeks in the butter and olive oil.
Season with salt and add wine.
Add the chicken stock and thyme, cover and cook over very low heat until leeks soften.
For the celeriac puree
Place the milk, cream and celeriac in a pot, season with salt, cover and cook over very low heat until the celeriac has softened.
Mix very well in a blender, season again with salt, add butter and mix again. Pass through a fine sieve and keep warm.
For the coriander sauce
Heat a pot and sauté the vegetables until golden brown.
Add wine and vinegar, add the coriander and simmer until the liquid condenses to about 1/3 of its initial volume.
Add the demi-glace and continue to simmer until the sauce thickens.
Pass through a sieve, add the butter and combine well. Keep warm.