Rinse the rice under cold water until the water runs clear.
In a medium saucepan, combine the rinsed rice and 2 cups of water. Bring to a boil over medium-high heat.
Once boiling, reduce heat to low, cover, and simmer for 15 minutes or until the water is absorbed and rice is tender.
Remove from heat and let the rice sit covered for 5 minutes, then fluff with a fork.
While the rice is cooking, prepare the chicken marinade by combining 2 tablespoons olive oil, 2 tablespoons lemon juice, minced garlic, dried oregano, ground cumin, salt, and black pepper in a bowl.
Add the chicken breasts to the marinade, coating them evenly. Let marinate for at least 10 minutes.
Heat a grill pan or skillet over medium-high heat.
Cook the marinated chicken breasts for 6-7 minutes on each side or until fully cooked and internal temperature reaches 165°F (74°C).
Remove chicken from heat and let rest for 5 minutes, then slice into strips.
Prepare the tzatziki sauce by combining Greek yogurt, chopped dill, lemon juice, minced garlic, salt, and black pepper in a small bowl. Mix well.
Assemble the bowls by dividing the cooked rice evenly among four bowls.
Top each bowl with sliced chicken, cherry tomatoes, diced cucumber, red onion, Kalamata olives, and crumbled feta cheese.
Drizzle each bowl with tzatziki sauce before serving.