Mix burger ingredients in a small bowl, adding ground beef last. You can use your fingers, but don't overwork the meat. Shape into 4 elongated patties to fit the bread portions. Cover and refrigerate the burgers until ready to cook.
Heat 2-sided contact grill to high. Add burgers and set timer for 4 minutes. Check with an instant-read meat thermometer inserted horizontally. They are done at 160°F. You can warm the bread and spread with pesto sauce while the burgers are cooking.
Optional garnishes to add color (but not too many calories) include roasted red peppers, black olives, pine nuts, fresh tomatoes, and lettuce.