Preheat oven to 350F.
Coat the chicken breasts in a thin layer of olive oil and distribute the 2 tsp salt across the two breasts.
Bake at 350F until cooked, roughly 30 minutes, or until the inside of the thickest part of the breast registers an internal temperature of 165F.
Remove the chicken breast and allow to cool.
Once cooled, dice the cooked chicken and mix with the chopped celery in a large bowl.
In a separate bowl, whisk together the mayonnaise, Greek yogurt & tarragon vinegar.
Add scallion and tarragon into the mayo and yogurt mixture and stir to combine.
Pour this mixture over the chicken and celery and stir to combine. Add salt and pepper to taste.