Chicken Souvlaki Gyro Style

Name: Chicken Souvlaki Gyro Style
Ingredients: 0.75 cup balsamic vinaigrette salad dressing; 3 tablespoons lemon juice; 1 tablespoon dried oregano; 0.5 teaspoon freshly ground black pepper; 4 skinless, boneless chicken breast halves; 0.5 cup seeded, shredded cucumber; 1 teaspoon kosher salt; 1 cup plain yogurt; 0.25 cup sour cream; 1 tablespoon lemon juice; 0.5 tablespoon rice vinegar; 1 teaspoon olive oil; 1 clove garlic, minced; 1 tablespoon chopped fresh dill; 0.5 teaspoon Greek seasoning; kosher salt to taste; freshly ground black pepper to taste; 4 large pita bread rounds; 1 heart of romaine lettuce, cut into 1/4 inch slices; 1 red onion, thinly sliced; 1 tomato, halved and sliced; 0.5 cup kalamata olives; 0.5 cup pepperoncini; 1 cup crumbled feta cheese