Drain the Cucumber: Shred the English cucumber, then use a paper towel or a clean kitchen towel to squeeze out as much excess water as possible. This step is vital to prevent a soggy salad.
Mix the Dressing: In a large bowl, combine the drained cucumber, Greek yogurt, dill, mint, lemon juice, olive oil, garlic, salt, and pepper. Whisk until the ingredients are fully incorporated.
Combine: Add the shredded chicken and sliced red onion to the bowl. Mix thoroughly until every piece of chicken is well coated in the tzatziki sauce.
Chill: Place the salad in the refrigerator for 30 minutes before serving to allow the flavors to meld.
Serve: Enjoy this salad tucked into pita bread, served on crackers, or as a high-protein topper for a fresh green salad.