Method:
Prepare burgers: mix salmon, garlic, mustard, tarragon, hoisin, cayenne pepper, egg, and breadcrumbs in a bowl and gently knead together until well combined. Form approximately 1/4 pound balls and then flatten into patties. Refrigerate patties for at least 1 hour (or up to 1 day).
Prepare the Miso Ketchup: grind sesame seeds in a spice grinder. Combine miso, mirin, and shoyu in a bowl and whisk together until well mixed. Set aside.
Preheat grill. Remove salmon from refrigerator, spray with cooking spray and season with salt and pepper. Place salmon on hot grill in 10 o'clock position for 2 to 3 minutes, then turn to the 2 o'clock position for an additional 2 to 3 minutes. Flip burgers and cook an additional 4 to 5 minutes, until burgers are cooked through. Serve on whole-grain buns with miso ketchup.