Turn on the oven to 300 F (275 F if it is really strong). Pat dry each pork shanks and liberally season with salt and pepper. Rough chop the onion, celery and garlic.

In a skillet over medium-high heat add the vegetable oil and sear the shanks on all sides, working in batches. Transfer them to a suitably large roasting pan/baking dish.

Lower the heat to medium and saute the chopped veggies until softened. Deglaze with a bit of the beer and thoroughly scrape off all the brown bits from the bottom of the skillet. Add the rest of the beer, the beef base and water (or beef stock). Stir.

Add the thyme, oregano and bay leaf and bring to boil. Pour the so prepared braising liquid over the shanks and tuck veggies and herbs. Tightly cover the pan with foil to make sure as little moisture as possible can escape. Transfer it to the oven and cook for about 2 ½ hours.

Take the pan out of the oven and check the shanks for tenderness. At this point the bones should be well exposed and the meat very tender. If not easily separated from the bones by minimal pressure from a fork, cover and braise a bit longer. If needed add a bit of water to replenish the braising iquid.

Keep checking every 15 minutes or so until satisfied with the tenderness of the pork. When the meat is fork tender, gently turn around the shanks or stand them upright, and cook in the oven uncovered at the same temperature for extra 15-20 minutes, until the exterior acquires an appetizing brown finish.

When the shanks are done browning, remove them from the pan and strain its entire contents into a sauce pan. Keep the liquid and discard the solids. Return the shanks to the pan and cover to keep warm.

Bring the strained liquids to simmer and let reduce until a thickish sauce forms. Taste and season with salt and pepper if needed. If you would like to speed up the thickening step add 1 tablespoon corn starch dissolved in 1 tablespoon cold water to the simmering liquid. It will thicken almost instantly.