Truth be told, I love a good hamburger with drippy cheese, oozing and dribbling down my chin. Turkey burgers don't ooze, and that's something I've learned to accept when I opt for healthy eating. However, this chipotle ketchup can drip and dribble with the best. The smoky chipotle flavor here is quite mild, as the recipe calls for the adobo sauce but not the actual chile peppers. If you like your sauces hot, add a bit of chopped chipotle chile (with or without seeds) right into the ketchup mixture. Greek yogurt keeps the burgers moist, so they can cook through without drying out. It's the same trick I use when I make turkey meatballs, and it works every time. You can make the ketchup ahead, even a couple of weeks ahead, and store it in the refrigerator.