Chop the hard-boiled eggs into chunky, bite-sized pieces and set aside in a bowl.

In the bowl with the chopped eggs, add finely chopped red onion, diced celery, and chopped parsley and dill. Mix well.

In a separate bowl, mix Greek yogurt, Dijon mustard, kosher salt, and ground black pepper until smooth.

Scoop the avocado flesh into the mixing bowl, drizzle with lemon juice, and mash gently to combine.

Fold the egg and vegetable mixture into the avocado dressing, being careful not to mash ingredients.

Taste and adjust seasoning with salt, pepper, or lemon juice as needed.

Serve immediately in bowls, on toast, or in lettuce cups; store leftovers with lemon juice to prevent browning.