Heat your oven to 240°C/Fan 220°C/Gas 9. Remove the pork from its wrapping. Pat dry. Leave it get up to room temperature.
Pour 1 tbsp coriander seeds into a pestle and mortar. Add 1 tsp salt, a good grinding of pepper and 1 tbsp olive oil. Bash to release the aromas. Put the pork in a roasting tin and massage the coriander salt all over, pushing it into the scores. Roast for 20-25 mins to crackle the skin.
While the pork cooks, trim the rhubarb, leaving the sticks whole. Zest and juice the orange.
After 20-25 mins, turn the heat down to 180°C/Fan 160°C/Gas 4 and roast for another 2 hrs till the meat is tender and cooked through.
Pierce the joint with the tip of a knife. Make sure the juices run clear. If not, cook a bit longer. Place the pork on a large plate. Cover with foil. Let it rest for 30 mins or more before carving.
While the meat rests, put the roasting tin onto a medium heat on the hob. Scrape the base of the tin to lift any flavourful bits. Pour in 100ml vegetable stock, white wine or beer and cook for 5 mins, stirring. Strain through a sieve into a jug and then
pour back into the tin.
Stir in the orange juice and 1 tbsp sugar. Add the rhubarb sticks to the gravy. If they’re too long to fit in the tin, halve them. Roast in the oven for 10-15 mins till just tender. Thickly slice the pork and serve with the orangey gravy and roasted rhubarb, scattered with the orange zest.
Swap shreds of leftover pork for the diced pork in our Honey Ginger Pork Ramen.