Preheat the oven to 200'C.
Peel and finely dice the garlic and shallots.
Heat a frying pan and then add the chicken, skin side down and seal on both sides. Once golden brown, remove the chicken from the pan, transfer to a baking tray and roast in the oven for 8-10 minutes. Rest for at least 5 minutes before serving.
Use the same pan to sweat the shallots until they are soft. Add the garlic and then cook for a further minute. Deglaze the pan with the white wine and reduce by half. Once the wine has reduced, add the chicken stock and then reduce this by half. Add the mustards to the stock and then add the double cream. Season with salt and pepper and add a squeeze of lemon.
Place the potatoes in a pan of salted water and bring to the boil. Cook until tender and drain. Once cool, slice into 5mm thick rounds.
Pick the thyme leaves from the stalk and finely chop. Peel the onions and thinly slice. Melt half of the butter over a medium heat. Add the onions and a pinch of salt and cook until completely soft.
Melt the remaining butter in a second pan and cook until foaming. Add the potatoes and cook until golden brown all over. Add the onions, thyme and seasoning.
Wash the salad and dry in a salad spinner.
Whisk together the sherry vinegar and mustard and then slowly add in the walnut oil, whisking constantly until the vinaigrette thickens. Season with salt and pepper and then use tongs to toss the dressing through the salad leaves.
Serve the chicken topped with the sauce, the Lyonnaise potatoes alongisde and finish with a handful of the dressed leaves.
«When preparing this dish feel free to cook the onions and sauce in advance and warm through before serving.»