In a large pot, bring cider vinegar, sugar, garlic powder, cayenne, and celery seed to a boil.

Reduce heat and simmer for 5 minutes.

Add the jalapeno pepper slices (and red bell pepper, if desired) and simmer for 4 minutes.

Use a slotted spoon to transfer the peppers into clean, sterile canning jars, packing the jalapeños semi-firmly within ¼-inch of the rim of the jar.

Turn heat up for the remaining syrup and bring to a full rolling boil.

Boil for 5 minutes.

Use a ladle to pour the boiling syrup into the jars over the jalapeño slices.

Insert a knife into each of the jars two or three times to release any trapped pockets of air.

Add more syrup if necessary. (*see notes for leftover syrup)

Wipe the rims of the jars with a clean, damp paper towel then screw on two-part canning lids.

If you do NOT want to properly can these, simply cool jars at room temperature for an hour and then store them in a sealed container in the fridge for up to 3 months.

Use proper canning procedures to store at room temperature for longer periods of time.

To can, place jars in a canner and cover with water by 2-inches. Bring the water to a full rolling boil. When it reaches a boil, set the timer for 10 minutes for half-pint jars or 15 minutes for pint jars. When the timer goes off, use canning tongs to transfer the jars to a cooling rack or kitchen towel. Leave them to cool, undisturbed, for 24 hours. When fully cooled, wipe them with a clean damp washcloth. Double check that they've sealed properly by pushing down on the center of the lid. It will not move if it is sealed.