Combine yogurt, celery, parsley, lime juice, mayonnaise, mustard, salt, and pepper in a medium bowl; mix well. Add salmon and mix well.Advertisement
Halve avocados lengthwise and remove pits. Scoop about 1 tablespoon flesh from each avocado half into a small bowl. Mash the scooped-out avocado flesh with a fork and stir into the salmon mixture.
Fill each avocado half with about 1/4 cup of the salmon mixture, mounding it on top of the avocado halves. Garnish with chives, if desired.