In a large pot, bring salted water to a rolling boil over high heat. Carefully add cauliflower florets and blanch them for 1-2 minutes until they turn bright white but remain crisp. Immediately transfer the florets to a bowl filled with ice water to stop the cooking process.

Once the cauliflower has cooled for about 5 minutes in the ice bath, drain it thoroughly in a colander. Use a clean kitchen towel or paper towels to pat the cauliflower dry, removing excess moisture.

In a large mixing bowl, combine the blanched cauliflower, halved cherry tomatoes, thinly sliced red onions, pitted black and green olives, and freshly chopped parsley. Gently toss the ingredients together until they are evenly distributed.

In a separate medium bowl, whisk together olive oil, red wine vinegar, Dijon mustard, minced garlic, dried oregano, dried basil, salt, and black pepper. Mix until the dressing is well emulsified and creamy.

Pour the dressing over the vegetable mixture in the large bowl. Using a spatula or large spoon, gently toss everything together until the vegetables are fully coated in the savory dressing.

Cover the bowl tightly with plastic wrap or transfer the salad to an airtight container. Place it in the refrigerator and allow it to marinate for at least 30 minutes.

Before serving, remove the salad from the refrigerator and give it a final toss to redistribute the dressing. Taste and adjust seasoning with more salt and pepper if needed.