Jeff Goldberg may be “just a kid from Jersey,” but he isn’t kidding around when it comes to sandwiches. The most popular item on the menu at his Route 58 Delicatessen, “The World’s Best Reuben,” is so fat with layer upon layer of thinly sliced red meat that the upper piece of grilled rye bread looks like a doll’s hat balanced precariously on top of a giant’s head.