Heat your oven to 200°C/Fan 180°C/Gas 6. Fill and boil a kettle. Halve the pomegranate. Place one half, cut-side down, in the palm of your hand. Place a sieve over a bowl and tap the pomegranate with a wooden spoon so the seeds tumble into the sieve. Repeat with the other half. Pop 2 tbsp of the pomegranate seeds in a separate bowl. Squeeze the remaining seeds in the sieve with the back of a spoon to extract as much juice as possible. Set the juice aside and discard the squeezed seeds.
Peel and roughly chop the parsnips and potatoes. Pop in a pan and pour in enough boiling water from your kettle to cover them. Simmer them for 15 mins till the veg is tender.
While the veg simmer, put a frying pan over a high heat. Rub the lamb neck fillet with 2 tsp olive oil and a pinch of salt and pepper. Place the lamb neck fillet in the frying pan and cook for 5 mins, turning the fillet over half way through. If your pan is ovenproof, place it into the oven to finish cooking the lamb for 15 mins. Or transfer the fillet to an ovenproof dish and roast for 15 mins.
While the lamb is roasting, crush 5 cardamom pods in a mortar and pestle (or use a small bowl and a jam jar or the end of a rolling pin). Remove the papery husks and leave the seeds in the mortar/bowl. Finely crush them.
Finely slice the cabbage half and place the shredded cabbage in a pan. Set aside. Roughly chop the parsley leaves.
The parsnips and potatoes should be cooked by now. Drain them and shake dry in the colander. Tip them back into the pan. Add half the butter, the ground cardamom seeds and ½ tsp cinnamon. Mash together with plenty of salt and pepper. Place a lid on the pan to keep the mash warm. Set aside.
Remove the lamb from the oven and place it on a warm plate or board to rest. Put the frying pan back on a low heat. Add the squeezed pomegranate juice, 2 tbsp honey and the remaining butter. Cook gently for 5 mins, stirring a few times, till syrupy and thick.
While the pomegranate glaze is cooking, pour boiling water over the sliced cabbage. Simmer for 2-3 mins till tender. Drain.
Thinly slice the lamb neck. Heap the parsnip mash onto two plates. Top with the lamb and drizzle over the glaze. Scatter over chopped parsley and the reserved pomegranate seeds. Serve with the cabbage.