Prep the chicken. If using rotisserie chicken, remove skin and bones, then shred or dice the meat.
Leftover baked or poached chicken works just as well.
Chop the veg. Mince the red onion, chop the celery (or cucumber), and roughly chop the fresh herbs. Keep everything bite-sized for an even mix.
Dress the avocado. In a large bowl, add the diced avocados. Gently mash about half of it with the back of a fork.
Leave the rest in chunks for texture. Add lemon juice, olive oil, mustard, garlic, paprika, salt, and pepper. Stir to create a creamy base.
Add the mix-ins. Fold in the chicken, onion, celery, and herbs.
Taste and adjust salt, pepper, and lemon juice. If you like a little heat, sprinkle in red pepper flakes.
Chill or serve. You can serve it right away or chill for 20–30 minutes to let flavors meld. Spoon into lettuce cups, scoop onto sliced cucumbers, or pile into a low-carb wrap.
Finish with extras. For a restaurant-style touch, finish with a drizzle of olive oil, a squeeze of lemon, and a pinch of flaky salt.