Prepare the Vegetables: In a mixing bowl, add the sliced cucumbers, diced avocado, crumbled feta cheese, thinly sliced red onion, and chopped parsley.
Whisk the Dressing: In a separate small mixing bowl, combine the olive oil, lemon juice, apple cider vinegar, minced garlic, dried oregano, kosher salt, and black pepper. Whisk until well combined.
Combine Ingredients: Pour the dressing over the salad ingredients in the mixing bowl and gently mix until well coated.
Taste and Adjust Seasoning: Taste the salad and adjust seasoning as needed.
Serve and Enjoy: Serve the salad immediately for maximum freshness.