Served this recipe from Williams-Sonoma last night for dinner. It was so good!! I made the mistake of using leftover hamburger buns instead of following the directions of using sourdough rolls, which would have stood up better to the sauce, resulting in a soggy burger. This did not affect the wonderful taste, I just would not make this mistake again. I used an 18-year old balsamic vinegar from Fustini's in this dish and it was wonderful. I also used my grill pan instead of the BBQ owing to the weather. It worked well. According to the recipe, the sandwiches can be served warm (which we did) or chilled. Prep time includes marinating time.