This is a recipe my mother has been making for years, and something she often makes for company because it is always well received. She learned about it from cousin Kristina, another source of all good things. Regarding the pan: A sheet pan is not recommended because the balsamic will reduce too quickly and burn. You want to use a pan that will fit the peppers snuggly. I find a 9x13-inch pan to be perfect for 1.5 lbs. of mini peppers, but something a little bit larger or slightly smaller will work well, too.