Melt 2 Tablespoons ghee or butter in a large deep dutch oven, sear two cross-cut shanks on both sides, about 8 mins total.
Remove shanks and add 6 peeled shallots, 10 garlic cloves and brown slightly in the fat for another 4 minutes.
Add 4 cups tomato puree, 2 cups water, 1/4 cup red wine vinegar, two
sprigs rosemary, 3 bay leaves. Cover and place in the oven at 300ºF for 3
hours.
Remove and break the shanks apart in the liquid with a fork, adding the
marrow to the sauce if it has not already fallen out of the bone. Remove
any large ligaments that are still intact. Bring to the boil on the
stovetop and reduce until it’s a thick sauce. Serve keto-style with
fried eggs and cauliflower rice or traditionally atop pasta or another
starchy main.