Fill a large pot with 3 to 4 quarts of water and add a generous pinch of salt. Bring it to a rolling boil, then drop in the cauliflower florets and blanch for 1 to 2 minutes until they turn bright white and are still crisp-tender. Immediately scoop them into a big bowl of ice water to stop the cooking.

Cool the florets in the ice bath for about 5 minutes, then drain them in a colander. Spread them on a clean kitchen towel or pat dry with paper towels until no excess water remains.

Put the dry cauliflower florets in a large mixing bowl. Add the halved cherry tomatoes, sliced red onion, halved black and green olives, and chopped parsley. Toss gently to combine.

In a separate small bowl, whisk together the olive oil, red wine vinegar, Dijon mustard, minced garlic, oregano, basil, salt, pepper, and red pepper flakes until creamy and well blended.

Pour the dressing over the vegetable mixture. Use a large spoon or spatula to toss everything gently until all ingredients are evenly coated.

Cover the bowl with plastic wrap or transfer the salad to an airtight container. Refrigerate for at least 30 minutes to let the cauliflower marinate and absorb the vinaigrette.

When ready to serve, stir the salad once more. Taste and adjust the seasoning with extra salt or pepper if needed.