After the vegetables have been cut according to the specifications in the ingredients list, heat one tablespoon of oil or lard in a heavy bottom oven safe pot over medium-high heat until shimmering and generously salt & pepper the pork shanks.
Brown the shanks in the fat, 2-3 minutes per side. Don’t peek before flipping and allow a nice brown crust to form. Remove the shanks from the pot and set aside on a plate.
Heat the oven to 250 F. Add up to an additional tablespoon of fat to the pot if needed, reduce the heat to medium low, and add the onion, carrot, garlic, diced leek, oregano, and a three finger pinch of salt & a few healthy cracks of black pepper. Sauté until slightly browned.
Add the stock, white wine, and orange supremes to your pot and return the pork shanks along with it. The liquid should only come about halfway up the osso buco- you don’t want to drown it or it will lose its nice brown crust you just worked so hard to achieve! Bring the liquid almost to a simmer. Don’t let it boil; tough meat is a bummer.
Once it comes to a simmer, cover the pot with a lid or aluminum foil and place on the middle rack in the oven. Cook at 250° 2.5-3 hrs, until it’s almost falling off the bone (should be tender & juicy but still hold together). Halfway through, at about the 1.5 hour mark, add in the halved leeks.
