Whisk the lemon juice, Greek yogurt, oregano, coriander, cumin, garlic, crushed red pepper, olive oil, salt and pepper in a small bowl until smooth.
Place the diced chicken in the bag and pour in HALF of the marinade (reserve the other half for later). Seal the bag and marinate the chicken while you prepare the rest of the meal (20-30 minutes). Skip ahead to preparing the rice and sauce. Then return to step 3 once you’re done.
Remove the chicken from the bag. Season with ¾ tsp more salt and a few very generous grinds of black pepper.
Heat the oil in a large heavy-bottomed cast iron or stainless-steel skillet over medium-high heat until the oil is HOT. Add the chicken pieces and cook without touching them until they are golden on the first side, about 3 minutes. Using tongs, flip the chicken. Reduce the heat to medium and cook until the chicken is cooked through and golden, another 2-3 minutes. Pour the reserved marinade over the chicken and cook until it is absorbed into the chicken, about 2 minutes.