I love this way of cooking pork, works best with pork loin, for pork belly and shoulder I have long cooked methods I prefer for those rich meats, but this citrus marinade helps tenderise what can be a slightly tough cut of meat.
Firstly, make your marinade.
Take 2 peeled and chopped cloves of garlic,1 tsp salt, half tsp pepper. Using a mortar and pestle, grind to a paste.
Add 2 tablespoons sherry or red wine vinegar, 2 tablespoons of white wine or dry sherry, the juice of a lemon and the juice of an orange, and mix together.
Pour this over your loin of pork joint in a small roasting pan - make sure it has no rind, and remove it if it has - don't throw it away, freeze it to add richness to stews and soups. Cover in cling film and marinade in the fridge for a couple of hours.
It will need roughly 1-1.5 hours in a medium oven. When you come to cook it, remove the cling film and add a chopped tomato and an ounce or so of unsalted butter. Roast uncovered, basting from time to time.
Rest it for 10 minutes before serving in very thin slices. Whilst it is roasting, bring the cooking juices to a simmer, remove any singed bits of tomato, turn off the heat and whisk in a slice or so more unsalted butter to thicken the sauce.
Do give it a go, it is really really good!