In a large mixing bowl, combine both types of olives with chopped celery, diced onion, and capers. Stir gently until mixed.

In a separate small bowl, whisk together olive oil, red wine vinegar, minced garlic, dried basil, dried oregano, crushed red pepper flakes, and salt.

Pour the dressing over the olive mixture, tossing gently to coat all ingredients. Avoid breaking the olives.

Cover the bowl or transfer olives to an airtight container. Refrigerate for at least 3 hours or overnight.