Slice the tomato and red onion, and cut the lemon into wedges. Lightly brush the pita bread with olive oil and toast it until slightly crispy.
Spread Tzatziki sauce on both sides of the toasted pita bread. Place two tomato slices on the pita, followed by the sliced red onion and shredded lettuce.
Heat the precooked gyro meat on the Blackstone griddle for 20-30 seconds per side, until warmed through. Add the gyro meat to the pita, then sprinkle feta cheese on top.
