Marinate the chicken: In a bowl, mix olive oil, lemon zest and juice, garlic, oregano, cumin, salt, and pepper.
Add chicken, toss to coat, and marinate at least 30 minutes (up to 12 hours) in the fridge.
Cook your base: Prepare quinoa, brown rice, or farro according to package directions. Fluff and let it cool slightly so it doesn’t wilt the greens.
Make the sauce: Stir Greek yogurt, grated cucumber, lemon juice, dill, garlic, olive oil, salt, and pepper. Taste and adjust lemon or salt.
Chill until serving.
Cook the chicken: Grill, roast, or pan-sear. For pan-searing: heat a large skillet over medium-high, add a drizzle of oil, and cook chicken 5–7 minutes per side (165°F internal). Rest 5 minutes, then slice.
Prep the veggies: Halve tomatoes, dice cucumber, slice red onion, and chop parsley.
Pat olives dry for better texture.
Assemble the bowls: Add a handful of greens and a scoop of grains to each bowl. Top with sliced chicken, tomatoes, cucumber, onion, olives, and feta.
Add sauce and finish: Spoon tzatziki over the top. Sprinkle with parsley and serve with lemon wedges for extra brightness.