Method:
To prepare the relish, toss all ingredients together in a large bowl. Set aside.
For the burgers, mix together water chestnuts, hoisin sauce, oil, green onions, garlic, mustard and cilantro in a large bowl. Add turkey and mix together with a fork until just combined. Form turkey mixture into 6 patties.
Spray a large skillet or grill with cooking spray and heat on medium high heat. Cook burgers, flipping once, until cooked through and golden brown, 6 to 7 minutes per side. Transfer burgers to toasted buns and top with lettuce and cucumber-pineapple relish.