Bring a large pot of salted water to a boil. Add the cauliflower florets and cook for 2–3 minutes until they are slightly tender but still crisp.
In a small bowl or jar, whisk together the olive oil, apple cider vinegar, lemon juice, Dijon mustard, oregano, salt, and pepper until well combined.
In a large bowl, combine the blanched cauliflower with Kalamata olives, green olives, capers, red onion, and cherry tomatoes.
Pour the dressing over the salad mixture and toss gently to ensure everything is coated evenly. Allow to sit for about 10–15 minutes before serving.
Serve the salad chilled or at room temperature.