Slow Cooker Pork Pot Roast

Name: Slow Cooker Pork Pot Roast
Ingredients: 2 tablespoons ghee; 8 leeks (or 2 medium onions) (whites only, thinly sliced); 6 garlic cloves (minced); 1 tablespoon tomato paste; 3 sprigs fresh thyme; ¼ cup chicken stock; ¼ cup dry vermouth; 1 (28-ounce) can fire-roasted diced tomatoes (drained); 1½ pounds medium carrots (peeled and cut into 1-inch chunks); 4 celery stalks (cut into 1-inch chunks); 1 small cabbage (cut into eighths (optional)); 1 tablespoon Red Boat fish sauce; 4 pounds boneless pork picnic shoulder roasts (trimmed and tied); 2 tablespoons Banyuls vinegar; Diamond Crystal kosher salt; Freshly ground black pepper