Preheat an outdoor grill for high heat and lightly oil the grate.

In a large bowl, mix together ground turkey, crushed crackers, egg, red pepper flakes, garlic powder, and onion until well combined. Form into four fat patties.

Cook patties on the preheated grill until no longer pink in the center, about 5 minutes per side. An instant-read thermometer inserted into the center should read at least 160 degrees F (70 degrees C).