Pound the salt, pepper and fennel in a mortar and pestle into a coarse powder
Pat the surface of the meat dry with paper towel and rub the fennel salt all over the surface. Scatter the onion, carrot and celery in the base of a flameproof baking dish and top with the pork
Bake at 230°C for 15 minutes. Reduce the heat to 180°C and bake for a further 45 minutes or until cooked. Remove pork from pan, cover with foil and stand in a warm place for 20 minutes
Pour juices from pan through a strainer into a jug and stand for 5 minutes before spooning off and discarding fat
Place the baking dish over moderate heat, add the port, wine, stock, cinnamon stick and rosemary and cook, scraping dish to dislodge any cooked on pork remnants from the bottom of the dish
Pour the skimmed cooking juices back into the pan along with any from the resting meat. Strain sauce through a fine sieve into a saucepan, add the figs and simmer gently for 10 minutes to reduce and thicken slightly
Remove cinnamon stick and rosemary if desired. Gradually whisk in the butter, a cube at a time melting between each addition. Keep warm while carving meat
