Whisk the marinade. In a bowl, combine olive oil, lemon juice and zest, garlic, oregano, cumin (if using), salt, and pepper.
It should smell bright and garlicky.
Marinate the chicken. Add chicken to the bowl and toss to coat. Cover and refrigerate for at least 30 minutes, or up to 8 hours. Longer marinades deepen the flavor.
Cook your grain. Prepare quinoa or brown rice according to package instructions.
Fluff and let cool slightly so it doesn’t wilt the greens.
Make the yogurt sauce. Stir together Greek yogurt, olive oil, lemon juice, grated garlic, herbs, salt, and pepper. Adjust lemon and salt to taste. Chill until serving.
Chop the veggies. Halve tomatoes, dice cucumber, slice onion, and pit/halve olives.
Pat veggies dry for the best crunch and to avoid watery bowls.
Cook the chicken. Grill, pan-sear, or bake. For pan-searing: heat a large skillet over medium-high, add a light drizzle of oil, and cook chicken 5–7 minutes per side (thighs may need longer) until golden and cooked through (internal temp 165°F/74°C). Rest 5 minutes, then slice.
Assemble the base. Divide greens and warm grain among bowls.
Add chickpeas if using.
Add toppings. Arrange tomatoes, cucumber, red onion, olives, and feta. Sprinkle with fresh herbs.
Finish with sauce. Top with sliced chicken and a generous spoonful of yogurt sauce. Drizzle with a little olive oil and an extra squeeze of lemon if you like.
Season and serve. Taste and add a pinch of salt, pepper, or a dusting of oregano.
Serve immediately or pack for later.