In a small bowl whisk together egg, onion powder, garlic powder, dry mustard, pepper and salt. Set aside.
In a medium size bowl gently mix together ground turkey, Italian sausage, onion, red pepper and parsley. Add egg mixture and breadcrumbs and mix with hands until well combined.
Form into approximately 4- 41/2 ounce patties 1/2 inch thick, making an indent in the center of each patty.
Preheat grill to medium high. Lightly brush each patty with oil and grill for approximately 5 minutes per side or until 170℉ is reached. Remove from grill and serve with Basil Mayonnaise.
Basil Mayonnaise
In a small bowl whisk together all ingredients and refrigerate until ready to use.