Combine lemon juice, olive oil, paprika, oregano, salt, pepper, and garlic powder in a small bowl.
Place the chicken breast in either a shallow dish or into a zip-top bag and pour the marinade over the chicken. Cover the dish or seal the bag and refrigerate for at least 20 minutes.
Cook the chicken
Heat the oven to 350°F (177°C). Remove the chicken from the bag and place it on a rimmed baking sheet. Bake for 25 minutes or until completely cooked through and the chicken is no longer pink.
Remove the chicken from the oven and cover it with foil to rest for 10 minutes before slicing.
Make the tzatziki sauce
Use a food processor or a box grater to grate or finely chop the cucumber.
Salt your finely chopped cucumbers and let them sit for a few minutes. Then, place the cucumbers in a clean dishtowel or cheesecloth. Gather the sides of the cloth into a tight bundle and squeeze firmly over a sink or bowl. This will help remove excess liquid from the cucumbers, preventing your tzatziki sauce from becoming too watery.
In a medium-sized bowl, mix the grated garlic, lemon juice, olive oil, Greek yogurt, and chopped dill. Then, add the well-drained cucumber and stir until everything is evenly combined.
To assemble
Add the rice to a bowl. Top with sliced chicken, tomatoes, cucumber, olives, red onions, a few tablespoons of the tzatziki sauce, and feta cheese.
Consider tucking pita chips into the sides of the bowl, if using, and garnish with fresh dill, mint, or parsley, if desired.
Notes
Avoid dry chicken: Use a meat thermometer to ensure the chicken is cooked to 165°F in the thickest part. This guarantees it's safe to eat without overcooking.
Let it rest: After cooking, let the chicken rest for a few minutes before slicing. This keeps the juices inside the meat for maximum flavor.
Change up your base: Experiment with different grains like rice, quinoa, orzo pasta, or cauliflower rice for a low-carb option.