1 1/2 – 2 pounds thick-cut steak (sirloin or new york strip work well)
1 medium cucumber, peeled and sliced + 1/2 teaspoon salt
2 cups cold plain Greek yogurt
4 teaspoons minced garlic
1/3 cup chopped dill, fresh or frozen (may sub 2 tablespoons dried dill)
1 1/2 tablespoons freshly squeezed lemon juice
1/2 teaspoon salt, or to taste
1/8 teaspoon black pepper, or to taste
Chop steak into 1-inch pieces and set aside. Combine oil, garlic, oregano, salt, pepper, and lemon juice and stir to combine. Combine steak and marinade in a large zip lock bag, press as much as the air out as you can, and seal. Chill for 1 hour or up to 24 hours (the longer you can marinate the more tender and flavorful the meat will be).
Spread cucumber slices out on a paper towel. Sprinkle generously with salt on both sides and allow to rest for 5 minutes. Wrap cucumber slices in paper towels, squeeze excess liquid out, and transfer to a food processor or blender. Add remaining sauce ingredients to blender and pulse until smooth and creamy. Chill until ready to use.
When ready to cook your kebabs, thread the steak pieces onto skewers and discard marinade. Grill over medium-high heat for 10-12 minutes, rotating throughout to ensure even cooking. Alternately you can bake them in a large baking dish arranged in a single layer at 400 degrees for 30-40 minutes until cooked through.
Garnish with chopped oregano and serve immediately with prepared tzatziki sauce.