In a mixing bowl, mix together the egg, turkey, crumbs, buttermilk and seasoning. I use very clean hands to get it all mushed together.
Form four patties, salt and pepper them to taste.
In another, smaller mixing bowl, mix together the tomato, cucumber and feta. Salt and pepper to taste and toss lightly. Refrigerate until needed.
Preheat grill. Grill turkey patties on both sides, about five minutes on each side.
Turkey should be cooked through and not pink.
Serve with Tomato Feta Relish on the top.