Preheat a grill or grill pan on medium heat.
Season the steak on both sides well with steak seasoning, salt, and pepper.
Heat the oil in a nonstick pan over medium heat. Saute the peppers and onions until soft, approximately 6 - 8 minutes. Remove from the heat, cover with a lid and set aside.
Cook the steak on both sides to your desired temperature using a thermometer. (see below) Once done allow the steak to rest on a cutting board for 3 - 5 minutes before slicing against the grain into thin slices.
In the meantime. Place the yogurt, cucumber, red onion, garlic, lemon juice, and dill in a blender. Blend until smooth. Season with salt and pepper to taste.
Warm the pita on both sides on a medium heat grill or in a saute pan for approximately 30 seconds per side.
Place the onions, peppers, lettuce, tomato, and sliced steak on the pita. Drizzle the sauce over top, garnish with cilantro and serve with chips.