Preheat your grill to its highest setting. Chuck the turkey, fish sauce, coriander, sesame oil and spring onions into a large bowl. Season generously with salt and pepper, then get your hands stuck in and work the ingredients well. The more you work the meat, the better the burgers will hold together when cooked. Shape the meat into two equal patties. Place the patties on your grill pan on a baking tray and grill the burgers for 5 minutes on each side or until they are totally cooked through. Check by slicing into one of the patties to make sure the meat is white all the way through with no raw pink bits left. Meanwhile, cut your burger buns in half. Mix together the yogurt and chipotle paste and spread over the burger buns. When your burgers are cooked, remove from the grill and build your dream burger, stacking it up with tomato and lettuce- the bigger, the better.