Slice the chicken breast into thin, even strips and place them in a medium mixing bowl.
Add the cumin, coriander, turmeric, garlic powder, smoked paprika, sea salt, and black pepper to the chicken, tossing until every piece is thoroughly coated.
Heat the olive oil in a large non-stick skillet over medium-high heat.
Add the seasoned chicken to the skillet and sear for 6 to 8 minutes, turning occasionally, until the edges are golden brown and the meat is cooked through.
While the chicken cooks, finely dice the cucumber, halve the cherry tomatoes, and mince the red onion to prepare the fresh salad.
In a small ramekin, whisk together the plain Greek yogurt, lemon juice, and dried oregano until smooth and creamy.
Portion the warm cooked brown rice into a bowl, then top with the spiced chicken and the prepared vegetable salad.
Finish the dish by drizzling the lemon-yogurt sauce over the top for a bright, tangy finish.