Marinate the chicken. In a bowl, whisk olive oil, lemon juice and zest, garlic, oregano, cumin, paprika, salt, and pepper. Add chicken and toss to coat. Let it sit at least 20 minutes (or up to 8 hours in the fridge) for deeper flavor.
Cook the grain. Rinse quinoa if using.
Bring broth to a boil, add quinoa or couscous, olive oil, and salt. For quinoa: simmer covered 15 minutes, rest 5. For couscous: remove from heat, cover 5 minutes, then fluff with a fork.
Prep the veggies. Chop cucumber, tomatoes, red onion, and bell pepper.
If using roasted peppers, blot excess moisture. Halve olives. Chop parsley.
Keep everything in separate bowls so it’s easy to portion later.
Make the tzatziki. Combine yogurt, grated cucumber (squeezed well), lemon juice, olive oil, garlic, dill, salt, and pepper. Stir until creamy. Taste and adjust with more lemon or salt.
Cook the chicken. Heat a large skillet over medium-high.
Add a drizzle of oil. Cook chicken 5–6 minutes per side (time varies by thickness) until the internal temperature reaches 165°F (74°C). Rest 5 minutes, then slice or cube.
Fluff and season the grain. Add a squeeze of lemon and a pinch of salt to the quinoa or couscous.
A drizzle of olive oil keeps it from clumping.
Assemble the bowls. Divide grain among 4 meal prep containers. Top with chicken, cucumber, tomatoes, red onion, bell pepper, and olives. Sprinkle with feta and parsley.
Add a lemon wedge.
Add the sauce smartly. Portion tzatziki into small lidded cups or keep it in a separate container. Don’t spoon it over the hot chicken; add it just before eating for the best texture.