Place all the ingredients into a bowl except the stale bread.Note: as the feta cheese will add saltiness to the mixture a little pinch of salt is all these burgers need.
In a small bowl, soak a slice of stale bread in warm water until it's completely saturated, then squeeze out the excess liquid and crumble it into the turkey mixture. Mix all of the ingredients together until they are well combined, then shape the mixture into four patties of equal size
Heat up your grill or grill pan to medium-high heat, then lightly brush each patty with olive oil before placing them on the grill. Cook for about five minutes per side, or until the internal temperature of the burgers reaches 165°F.
Serve your Mediterranean-flavored turkey burgers on toasted buns with your favorite toppings.