With a small knife, pierce top of roast. Force garlic slices into the cuts. Sprinkle the roast with salt and pepper. Place bay leaves in the bottom of the roasting pan, and set roast on top of bay leaves, fat side up. Mix vinegar and thyme in a small bowl, and pour over the top of the roast.
Bake in the preheated oven 3 hours, or until an internal temperature of 145 degrees F (63 degrees C) is reached. Using a baster or spoon, baste the drippings over the roast frequently while it is cooking. Let the roast rest for 10 minutes when done before slicing.