2 large bulbs fennel (approx. 1kg/2 1/4lbs total, though less wouldn't matter)
100 millilitres cold-pressed rapeseed oil (or extra-virgin olive oil, plus more for drizzling on the chicken when cooking)
2 seville oranges (zested and juiced, or zest and juice of 1 eating orange and juice of 1 lemon, about 100ml /scant half cup of juice)
2 teaspoons Maldon sea salt flakes
4 teaspoons fennel seeds
4 teaspoons Dijon mustard
12 chicken thighs with skin on and bone in
Method
Remove the fronds from the fennel and put them in a resealable bag in the fridge for serving. I discard (that’s to say, eat) the tubey bits of the fennel, but if you have a roasting tin big enough, use everything. Cut the bulbs of fennel into quarters and then cut each quarter, lengthways, into 3. Leave on the chopping board while you get on with the marinade.
Placing a large freezer bag in position inside a wide-necked measuring jug or similar, pour in the oil, add the orange zest and juice (and lemon juice, if using), and spoon in the salt, fennel seeds and mustard. Stir briefly to mix.
Remove the bag from the jug and, holding it up, add a quarter of the chicken pieces, followed by a quarter of the fennel pieces, and so on until everything’s been used up.
Seal the bag tightly at the top, lay the bag in something like a lasagne dish and squelch it about so that you make the small amount of marinade cover as much of the chicken as possible. It will look as if it isn’t enough, but it is, I promise. Leave in the fridge overnight or up to 1 day.
When you want to cook, remove the marinating chicken and fennel from the fridge and tip the contents of the bag — marinade and all — into a large shallow roasting tin (I use a tin that measures 46 x 34cm with a lip of 1.5cm/half-sheet pan with a lip of ½ inch). Using tongs, or whatever implement(s) you prefer, arrange the chicken pieces so that they are sitting, skin-side up, on top of the fennel. Leave it for 30 minutes or so, to come up to room temperature while you preheat the oven to 200ºC/180°C Fan/gas mark 6/400ºF.
Drizzle some more golden oil onto the chicken, and cook in the oven for 1 hour, by which time the fennel will be soft and the chicken cooked through and bronzed on top.
Put the chicken and fennel onto a warmed serving plate and put the pan over a medium heat (use a saucepan if your tin isn’t hob-friendly) and boil the juices, stirring as you watch it turn syrupy; this should take about 1½–2 minutes in the tin, and about 5 in a saucepan.
Pour the reduced sauce over the chicken and fennel, and then tear over the reserved fennel fronds.