Step 1
For the dressing, in a food processor, puree the avocado, yogurt, herbs, lemon juice, scallions, anchovies (if using), garlic, and hot sauce; season with salt and pepper. Transfer the dressing to a large bowl.
Step 2
Shred or dice the chicken. (Reserve the skin and bones for stock.) You should have about 4 cups of meat.
Step 3
Mix the chicken, celery, chopped onion, pimientos, and chile into the dressing; season. Build sandwiches with the toast, chicken salad, lettuce, tomatoes, and onion.