Cucumber Dill Sauce:
Combine sour cream, mayonnaise, lemon juice, garlic, dill, cucumber, lemon pepper, and salt in a bowl and whisk.
Place shrimp in a bowl with olive oil and blackening seasoning. Grill on either side for 3 minutes until firm.
At the same time, warm pita on a grill or in the oven for 1-2 minutes or until soft.
Spread sauce on warm pita then place lettuce, onions, peppers, shrimp, and feta in that order. Add sauce to the top and finish with feta. Wrap in foil sheets for service.