Combine the onions, red wine vinegar, sugar and vinegar for at least 30 minutes.
Set aside until ready to use.
Combine the spices and cilantro with the ground turkey.
Form into 6 thin patties.
Heat the outdoor grill on medium heat.
Cook the burgers 4 minutes per side.
Let rest for 2 minutes.
Heat the oil skillet on medium heat.
Add a tortilla to the skillet and top with a good amount of cheese.
Add one of the burgers and top with more cheese and the second tortilla.
Cook until browned and the cheese is melted - about 3 minutes per side.
Cook in batches - depending on the size of the skillet.
Serve the burger topped with the pickled red onions and enjoy!