Wash the celery. You're going to use enough (depending on the specific size) in this recipe to fill 16 oz. jar.
Add the celery, garlic, dill, mustard seed, yellow onion, and peppercorns into your jar. Don't worry that the spices settle at the bottom, they will rise up again and evenly distribute their flavor when you add the brine.
Brine:
Mix the vinegar, water, salt, and sugar in a stainless steel pan and bring to a boil.
As soon as it reaches a good boil, pour it over the celery mixture in the jar until the celery is just covered.
Put the top on immediately and put into the refrigerator.