2 Little Gem lettuces, leaves separated
4 onions, peeled, sliced thinly
Β½ shallot, peeled, finely diced
5 sprigs thyme
1 tsp Dijon mustard
450ml/16fl oz chicken stock
salt and freshly ground black pepper
3 tbsp olive oil
1 tbsp white wine vinegar
40g butter
1kg/2lb 2oz free-range or organic chicken