Dice the zucchini into bite-sized pieces or half-moons. Toss with ½ teaspoon salt in a colander and let sit over the sink for 20 to 30 minutes to release excess water.
Pat the zucchini dry with a clean towel or paper towels. This keeps the salad crisp instead of watery.
Make the Dressing
In a small jar or bowl, combine the olive oil, red wine vinegar, lemon juice, minced garlic, oregano, salt, and pepper. Whisk or shake until cloudy and emulsified.
Combine and Serve
Add the drained zucchini, tomatoes, olives, and red onion to a large bowl. Pour the dressing over and toss to coat.
Scatter the feta, parsley, and dill over the top and toss gently. Chill 15 to 30 minutes, then serve cold.
Notes
Salt the zucchini: Raw zucchini holds a lot of water. The salt-and-drain step is the single most important move for a crisp, non-watery salad.
Use small zucchini: Firmer flesh and fewer seeds means it stays crunchy.
Dress close to serving: For best texture, toss everything together within an hour of eating.
Make it a meal: Add chickpeas, flaked tuna, cooked salmon, or sliced grilled steak.