1Juice one lemon into a small bowl. Add 2 tbsp olive oil, minced garlic, oregano, salt, and pepper. Stir together to make a marinade.
2Pat chicken dry and place in a shallow dish. Pour half the marinade over chicken, turn to coat, and let sit for 15 minutes while you prep everything else.
3Combine the rice and 4 cups water in a saucepan and bring to a boil. Cover, reduce the heat to low, and simmer 18 minutes until the water is absorbed. Fluff with a fork and set aside.
4Heat a grill or grill pan to medium-high. Oil the grates. Grill chicken 6 to 7 minutes per side until cooked through and charred in spots. Transfer to a cutting board and let rest 5 minutes, then slice into bite-size pieces.
5Whisk the juice of the second lemon with remaining 1 tbsp olive oil to make a finishing drizzle.
6Divide cooked rice among four bowls. Top each with sliced chicken, cucumber, tomato, olives, red onion, and feta. Drizzle with lemon-oil dressing and serve.