Put the rabbit pieces in a heavy, covered casserole. Mince the garlic and the onion and add to the casserole with the tomatoes, oil, capers, caper vinegar, sherry, orégano, salt, and pepper. Cover and simmer gently for about 1½ hours. Add the potatoes and cook for a further 30 minutes.
Young rabbits will cook in about 2 hours; older ones take up to 3 hours, so allow for this when adding