Marinate the chicken: In a bowl, whisk olive oil, lemon juice, lemon zest, garlic, oregano, cumin, paprika, salt, and pepper. Add chicken and toss to coat.
Cover and marinate at least 30 minutes, up to 8 hours in the fridge.
Make the tzatziki: Stir yogurt, grated cucumber, lemon juice, dill, garlic, salt, and pepper. Adjust to taste. Chill until serving so it thickens slightly.
Prep the base: If using cauliflower rice, sauté it in a little olive oil with a pinch of salt over medium heat for 5–7 minutes, until tender but not mushy.
If using greens, chop and set aside.
Chop the veggies: Halve tomatoes, dice cucumber, slice onion, and halve olives. Crumble feta and chop herbs.
Cook the chicken: Heat a skillet or grill over medium-high. Cook chicken 5–6 minutes per side (thighs may need a bit longer) until browned and cooked through.
Let rest 5 minutes, then slice.
Mix the quick dressing: Whisk olive oil, vinegar or lemon juice, Dijon, oregano, salt, and pepper.
Assemble the bowls: Add cauliflower rice or greens to each bowl. Top with sliced chicken, tomatoes, cucumber, onion, olives, and feta. Spoon tzatziki over the top and drizzle with dressing.
Finish with fresh herbs and a squeeze of lemon.
Taste and adjust: Add more salt, pepper, or lemon as needed. A little extra olive oil can add richness if desired.