Whisk the sauce ingredients in a small bowl and set aside
Heat half of the oil in a pan over medium heat
Add the sliced shallots and cook slowly tossing frequently until they are nicely browned. This takes about 15 minutes. Once browned moved to a paper towel lined plate
Meanwhile, combine turkey, grated apple, Dijon, thyme, sage, salt and pepper. Mix with hands to combine but do not overwork the mix. Make 4 burger patties
Add remaining oil to pan and allow it to heat up
Add burgers to pan and cook for 4 minutes covered
Flip burgers and cook for 2 minutes then divide onions evenly over the 4 burgers.
Add brie slices to top of onions, cover and cook about 2-3 minutes longer or until brie is nicely melted. Burger temperature should read 165˚ at thickest part
Remove to plate and add apple slices to top of burgers
Enjoy!