Start by hard-boiling the eggs. Place the eggs in a pot, cover them with water, and bring to a boil. Once boiling, cover the pot and remove it from heat. Let it sit for about 9-12 minutes, depending on how firm you like your yolks. After the time is up, transfer the eggs to an ice bath to cool before peeling.
While the eggs are cooling, take your ripe avocado and slice it in half. Remove the pit and scoop the flesh into a mixing bowl. Using a fork, mash the avocado until smooth but still a bit chunky. This texture adds a nice bite to your egg salad.
Once the eggs are cool, chop them into small pieces and add them to the bowl with the mashed avocado. Then, add the Greek yogurt, Dijon mustard, lemon juice, chopped red onion, and chopped celery. Season with salt and pepper to taste.
Using a fork, gently mix all the ingredients together until well combined. Be careful not to overmix, as you want to keep some of the egg and avocado chunks for texture.
Give your egg salad a taste and adjust the seasoning if necessary. If you like a bit more tang, feel free to add an extra splash of lemon juice or a pinch more mustard.
Transfer the egg salad to a serving dish. If desired, sprinkle with fresh dill or parsley for an extra pop of flavor and color. Serve it on whole grain bread, in lettuce wraps, or atop a bed of greens for a refreshing meal.