Spray a saute pan with nonstick oil and heat over medium heat.
Once hot, add the four Quorn filets and cook for 6 minutes.
Flip the filets and cook for 3-4 more minutes. Remove from heat and set aside.
Cut the filets into strips, lengthwise. Add 3 of the filets to the food processor, and half of the other 1. Set aside the other half, or add it if you don't want a light chunky texture in your chicken salad. Finely chop the remaining half of the filet.
Pulse the food processor a few times to get the chicken pieces broken into smaller pieces but not completely pulverized.
Add the celery, onion, and chives and pulse a few more times. it should be breaking into a chicken salad-resembling texture that kind of looks like cooked couscous.
Remove from the food processor into a large bowl and add the seasonings and Veganaise. Use a spaula to mix thoroughly. Add in the chopped filet if you're doing that.
Season to taste, and add veganaise as desired for a smoother chicken salad.
Let the flavors mingle in the fridge for at least 2 hours. Serve on a sandwich, with crackers, or eat with a spoon!