Preheat your oven to 325°F (165°C).
In a small bowl, add the salt. Rub the salt all over the pork shanks, making sure to get into all the crevices.
In a large roasting pan, place the beer, chicken stock, onions, onions, garlic, bay leaves, and caraway seeds. Place the salt crusted pork shanks in the roasting pan standing up right. They need to have a little space so don't overcrowd the pan. Cover tightly with aluminum foil.
Place the roasting pan in the preheated oven and cook for 2 to 2.5 hours. Remove from the oven and remove the foil. Now you want to check to see if the skin is soft and the meat is tender. Using a small paring knife, insert the knife through the skin and into the meat. The knife should insert easily into the center of the shank. It should feel like the meat will fall off the bone. If it is not, cover the pan with aluminum foil and place back in the oven for another 30-45 minutes.
When the shanks and skin are tender, remove the aluminum foil. Increase the oven temperature to 425 F (220C) and place the roasting pan back in the oven.
While the oven is preheating, remove the shanks and place on a plate temporarily. Using a strainer set over a medium sized pot, strain the liquid into the pot reserving the liquid. Use a rubber spatula and push a little on the solids in the strainer. You don't need to push too hard. You only want a little of the solids in the pot.
Once the oven reaches 425 F, place the shanks back in the roasting pan and place in the oven uncovered. Continue roasting for about 25-30 minutes, or until the skin is crispy and golden brown. Keep a close eye on them to ensure the skin doesn't burn.
Bring the liquid up to a simmer. Mix the cornstarch and water together until combined and smooth and slowly pour into the sauce until it's thickened. You might not need all of it. Continue to simmer for about 15 minutes. Taste and adjust seasoning if necessary.
Once the skin is crispy remove from the oven. Plate the shanks and serve with the Dark Beer Sauce.