Slice cucumbers into half-moons or quarters about ¼-inch thick. Toss with ½ teaspoon salt in a colander set over a bowl. Let sit 15 minutes, then rinse and pat dry.

Season chicken breasts with salt and pepper. Heat 1 tablespoon olive oil in a skillet over medium-high heat. Cook chicken 5-7 minutes per side until golden and internal temperature reaches 165°F. Let rest 5 minutes, then dice into bite-sized pieces.

In a small bowl, whisk together olive oil, red wine vinegar, lemon juice, Dijon mustard, minced garlic, ¼ teaspoon salt, and ⅛ teaspoon black pepper.

In a large bowl, combine cucumbers, chicken, red onion, dill, mint, and parsley. Pour dressing over and toss gently. Taste and adjust seasoning.

Let salad rest 10 minutes before serving to allow flavors to meld. Serve cold or at room temperature.