Heat oil in a fry pan over medium-high heat, add celery, apples, green onions and garlic and sauté until tender.
Add turkey to a large bowl along with sautéed mixture, salt, pepper, tarragon, lemon juice, parsley and mango chutney. Mix well. Shape into 4 burger patties. Refrigerate until ready to cook.
Cook on medium high grill 7-10 minutes per side or in 375ºF oven about 20 minutes until internal temperature reaches 165ºF. Top with 2 slices of marble cheddar and allow to melt a bit.