Snip off the fronds from the top of a bulb of fennel and reserve for a garnish. Cut the fennel top-to-bottom into segments
and scatter in a shallow casserole dish. Add chicken thighs. Make a marinade by combining 50ml olive oil, the zest and juice
of 2 seville oranges, 2 tsp fennel seeds, a Tbs Dijon mustard and a tsp sea salt. Pour this over the chicken and fennel,
cover and leave for several hours in the refrigerator, turning once or twice. When ready to cook, bring to room temperature
for an hour or so, then cook uncovered in a 180°C oven for an hour, basting from time to time, until the fennel is soft and
the chicken is cooked and golden brown. Serve garnished with the reserved fennel fronds.