In 5-quart Instant Pot, stir steak, half the garlic, seasoning, oil, salt and pepper; add stock. Place lid on Instant Pot and close pressure valve to seal; pressure cook on high 20 minutes. Quick release pressure; let stand 10 minutes before removing lid.
In medium bowl, stir cucumber, yogurt, dill, lemon juice and remaining garlic. Makes about 1 cup.
Tear 4 (12-inch) squares aluminum foil. Spread 1 side of each pita bread with yogurt mixture; top with steak mixture, tomato and onion. Roll pita around fillings to enclose; wrap tightly in foil.