Slice the chicken breast into thin, even strips and place them in a medium mixing bowl.
Add the olive oil, cumin, smoked paprika, turmeric, garlic powder, sea salt, and black pepper to the chicken, tossing until every piece is thoroughly coated.
Heat a large non-stick skillet over medium-high heat. Once hot, add the chicken in a single layer and sear until golden brown and cooked through, approximately 3-4 minutes per side.
While the chicken is crisping, whisk together the Greek yogurt and lemon juice in a small ramekin to create a smooth sauce.
Prepare the bowl base by combining the chopped romaine lettuce, diced cucumber, halved cherry tomatoes, and thinly sliced red onion.
Top the fresh vegetable medley with the warm shawarma chicken and finish by drizzling the lemon-yogurt sauce over the top.