1. Mix together beef, pork, feta, green onions, dill, parsley, garlic, lemon zest, lemon juice, salt, pepper and oregano. Shape into six 1/2-inch thick burgers.
2. Preheat XL Smokeless Grill. Grill burgers for 5 to 6 minutes per side or until grill-marked and internal temperature reaches 165˚F.
3. Assemble burgers, tzatziki sauce, lettuce, tomatoes and red onion in buns.