In a medium bowl, whisk together the lemon juice, garlic, salt, mustard, and dill. Slowly stream in the oil, whisking until very smooth.
Add the celery, onion, and eggs to a large bowl. Add the dressing, stirring to combine. Allow to sit for 5 minutes for the dressing to absorb. Taste and add additional salt or dill if desired. Serve immediately or store covered in the fridge for up to 5 days.