Whisk together olive oil, lemon juice, lemon zest, minced garlic, oregano, salt, and pepper in a bowl. Let the chicken soak for at least 20 minutes.

Grill the marinated chicken over medium-high heat for 5–6 minutes on each side until cooked through. Let it rest before slicing.

Combine Greek yogurt, grated cucumber, lemon juice, minced garlic, fresh dill, and a pinch of salt in a bowl. Chill in the refrigerator.

Toss together chopped romaine, kale, diced cucumber, sliced red onion, olives, and crumbled feta cheese in a large bowl.

Divide the salad mix into bowls, topping each with grilled chicken and tzatziki.

Garnish with fresh dill and lemon wedges. Serve immediately or refrigerate components separately.