Season the rabbit legs. Melt the butter in a heavy-based casserole pan and sear the rabbit legs. Remove from the pan and drain.
Swill the casserole with the vinegar and boil to reduce by two-thirds. Add all the remaining ingredients and bring to the boil. When boiling, add the rabbit back to the casserole, cover and cook gently until the meat falls freely off the bone
Take out the rabbit and set aside. Boil the cooking liquor to reduce it to a sauce-like consistency (it will coat the back of a spoon)
Adjust the seasoning and return the rabbit to the pot to warm through