In a medium bowl, toss the diced chicken breast with olive oil, dried oregano, garlic powder, salt, and pepper. Let it marinate for at least 10 minutes if possible.
Heat a large skillet over medium-high heat. Add the seasoned chicken and cook for 6-8 minutes, stirring occasionally, until cooked through and golden brown. Remove from heat and set aside.
While the chicken cooks, combine Greek yogurt, lemon juice, minced garlic, and a pinch of salt in a small bowl. Stir until smooth. Mix in finely chopped fresh dill.
Halve the cherry tomatoes, dice the cucumber, and thinly slice the red onion.
Assemble the bowls starting with cooked jasmine rice as the base. Layer chicken, cherry tomatoes, cucumber, red onion, crumbled feta, and sliced kalamata olives. Drizzle with tzatziki sauce and garnish with fresh dill.
Serve immediately or refrigerate for later. Reheat chicken and rice before assembling if storing leftovers.