Prepare the cucumberWrap the grated cucumber in a clean towel and squeeze out the excess moisture.
Mix the tzatziki sauceIn a large mixing bowl, combine Greek yogurt, dill, lemon juice, minced garlic, salt, pepper, and the squeezed cucumber. Stir until well blended.
Add the chicken and onionShred the rotisserie chicken and add it to the bowl along with the diced red onion. Mix until everything is evenly coated with the sauce.
ServeServe immediately in pita bread, on toast, with crackers, over a salad, or wrapped in lettuce leaves.
StoreKeep leftovers in an airtight container in the fridge for up to 5 days. Do not leave out for more than 2 hours.