In a medium bowl, mix the chicken breast cubes, red onion, celery, cilantro, and feta.
In a small bowl, whisk the mayonnaise, Dijon mustard, lemon juice, minced garlic, kosher salt, and black pepper.
Pour the dressing on the chicken salad and mix well to combine.
Serve immediately, or chill for an hour to allow the flavors to meld. Mix again before serving.
Video
Notes
If you need to cook the chicken, use two 8-ounce raw chicken breasts. Spray them with oil, lightly sprinkle them with salt and pepper, and bake them in a 450°F oven until cooked through, for about 20 minutes.
While you can certainly serve this salad as soon as it's ready, I like to let it rest for just a little while (15 minutes or so) at room temperature, allowing the flavors to meld. I then stir it again before serving.
This is a basic recipe, and you should feel free to add to it as you like. Tasty additions include ½ cubed avocado, grated or diced hard-boiled egg, and chopped cooked bacon. Sometimes, I add a handful of cherry tomatoes, as shown in the photos on this page.
You can keep the leftovers in the fridge, in an airtight container, for 3-4 days. Give them a gentle stir before serving them. I don't recommend freezing this salad.