Heat half the oil with a handle in a big frying pan or shallow casserole. Brown the chicken until it is golden, then set aside. Heat the remaining oil and boil the onions for 5 minutes until loosened.
Nestle the thighs between the onions and add the parnips. Mix the mustard and honey in the inventory, then pour in. Scatter over the thyme, then take to a cooler. Cover, then cook for 30 mins (or longer, see tip) until the chicken is tender, then season. Serve with steamed greens.