Add the cider vinegar to the pan, minding the vigorous effervescent and steam. Utilizing a spatula or wood spoon, scrape up any browned bits on the underside of the pan. Stir consistently, cooking till the vinegar has diminished to about 1 tablespoon. Pour within the arduous cider, scrape up any browned bits once more, add 10 of the thyme sprigs and the bay leaves, and return the warmth to medium-high. Let the cider bubble away till it has diminished by round two-thirds, 8 to 10 minutes (in case you’re utilizing a spherical Dutch oven, chances are you’ll need to take it a bit farther, as a result of the liquid gained’t cook dinner down as readily within the oven). Flip off the warmth.
