Slice the rye sourdough bread.
Boil the chicken breast and shred it along the grain.
Slice the avocado.
Wash and prepare the lettuce.
Slice the tomato.
Place lettuce, chicken breast, avocado, and tomato in order on the sourdough bread.
Add a small amount of mayonnaise or mustard to taste.
Cover with another slice of bread to finish the sandwich.