Some think a good waiter is someone who sneaks an extra shrimp into your cocktail. Me, I prefer a waiter who gives away the chef’s secrets. I got this recipephany many years ago from a waiter at Lala Rokh on Beacon Hill, an elegant Persian restaurant near John Kerry’s townhouse on Louisburg Square. It was my Dad’s birthday, when the kids were home and my folks could still negotiate at least some of the steep walk to the door. We started with this appetizer called zaitun-e parwardeh. It mesmerized me so much that—sort of like the Men in Black’s Neuralizer—it wiped out my entire memory of the rest of the meal. Sweet, tart, salty,…