Cook and peel the hard boiled eggs. You can either follow my stovetop method, or use the Instant pot to cook on low pressure for 6-7 minutes with the eggs on the trivet and 1 cup of water in the base. Either way, transfer cooked eggs to an ice bath before peeling.
Chop the hard boiled eggs and add to a large bowl.
Chop or mash the peeled avocado. Add to the eggs. Add mayonnaise and mustard. Stir well to combine. You can add more mayo and/or mustard if you prefer. Add salt and pepper, to taste.
Egg salad will keep in the refrigerator for at least 5 days if stored in an air tight container.