Cook ground beef, onion, greek seasoning, pepper, and 1/4 tsp. salt in a large skillet over medium-high heat, stirring often, 7 to 9 minutes or until beef crumbles and is no longer pink; drain well on paper towels.
Stir together cucumber, sour cream, dill, garlic and remaining 1/4 tsp. salt. (I often make this ahead of time and keep it in the refrigerator, as it allows for the flavors to infuse together.)
Once everything is done, it is time to put it together. Spoon beef mixture, tomatoes, lettuce, and feta into the pita pocket, then top with cucumber sauce. Eat and Enjoy! You will be back for more.