Special chicken stew

INGREDIENTS

• salt
• freshly ground black pepper
• 4 higher-welfare spring chickens or poussins
• 1 small handful fresh parsley, leaves picked, stalks kept
• 1 bunch fresh tarragon, leaves picked, stalks kept
• 4 teaspoons wholegrain mustard
• 2 heaped tablespoons plain white flour
• extra virgin olive oil
• 1 white onion, peeled and finely chopped
• 2 cloves garlic, peeled and finely sliced
• ½ heart celery, trimmed back and finely sliced
• 2 good knobs butter
• 2 wineglasses crisp white wine
• 565 ml organic stock
• 3 gem lettuces, quartered
• 1 small bunch seedless grapes, washed and halved