Wash celery stalks, then use a vegetable peeler to remove the stringy fibers. Slice into 4" to 5" lengths.
Divide celery between two sterilized pint-sized mason jars. Slice peeled garlic cloves and serrano pepper in half, then divide between the jars. Top each jar with fresh dill.
Prepare Pickling Solution
Prepare pickling liquid by adding vinegar, water, peppercorns, coriander seeds, pickling salt, and sugar into a saucepan. Add a slice of onion and heat the mixture over medium heat, whisking until the salt and sugar dissolve. Do not boil.
Allow the pickling liquid to cool slightly then strain into the jars until the celery is totally submerged. Add lids, then hand-tighten collars. Wait at least one day before tasting the celery. The flavor will improve with more time. Store in the refrigerator for up to 3 months.
Notes
I only had 12 ounces of celery to pickle but could have easily filled the jar with more celery. So if you have less than a pound of celery, don't let that stop you!
Straining the onion slices first makes pouring the brine into the jars easier.
Use crisp, fresh celery stalks for the best results.
Wash celery thoroughly to remove any dirt or debris, especially towards the root, where dirt collects.
When slicing the celery, aim for uniform sizes.
When adding the pickling solution, don't forget to leave about ½ inch of headspace at the top of the jar.
If the pickled celery floats, use pickling weights to keep them submerged in the liquid.
Process the jars in a boiling water bath for about 10 minutes if you want shelf-stable pickled celery.
Keep in mind that if you water bath the canned pickled celery, the texture will get softer.