800 g (1 lb 4 oz) potatoes, peeled and cut into chunks
200 g (7 oz) celeriac, peeled and cut into chunks
4 x 150 g (5 oz) chicken breasts
8 tarragon sprigs
125 ml (4 fl oz) white wine
250 g (8 oz) green beans, trimmed
50 g (2 oz) butter
salt and pepper
Cook the potatoes and celeriac together in a pan of boiling water for 10–12 minutes, until tender.
Meanwhile, place each chicken breast on a large piece of greaseproof paper. Place 2 tarragon sprigs on each, then sprinkle with 2 tablespoons white wine and pepper. Fold the paper to securely enclose the chicken and liquid and place the parcels on a baking sheet or in a roasting tin.
Bake in a preheated oven, 200˚C (400˚F), Gas Mark 6, for 15–18 minutes.
Meanwhile, steam the beans for 3–4 minutes.
Drain the potato and celeriac and mash together with the butter. Season with salt and pepper.
Serve the chicken on a bed of mash, topped with the beans. Pour over any cooking juices.