Wash the hot peppers thoroughly.
Cut off and discard the stem ends.
Remove most of the seeds and pith, depending on the desired heat level.
Finely chop the peppers in a food processor until they are uniform and small in size.
Transfer the chopped peppers to a heavy-bottomed 8-quart stockpot.
Add the distilled white vinegar, canning salt, prepared yellow mustard, and granulated sugar.
Stir until the ingredients are fully combined.
Place the stockpot over medium-high heat.
Bring the mixture to a rolling boil.
Reduce the heat to maintain a low boil.
Cook for 10 minutes, stirring frequently to prevent sticking.
While the pepper mixture cooks, whisk the water and Clear Jel together in a separate bowl until smooth.
After the pepper mixture has cooked for 10 minutes, remove the stockpot from the heat.
Slowly whisk the Clear Jel mixture into the hot pepper mixture.
Continue whisking until the slurry is evenly incorporated.
Return the stockpot to the heat.
Bring the mixture back to a boil.
Continue whisking until the mixture boils throughout and thickens evenly.
Remove the thickened mustard mixture from the heat.
Carefully ladle the hot mustard into prepared sterilized pint canning jars.
Leave approximately 1/4 inch of headspace in each jar.
Wipe the rims of the jars clean with a damp cloth.
Place lids on the jars.
Apply rings and tighten until fingertip-tight.
Place the jars in a boiling water bath canner.
Ensure the jars are covered by at least 1 inch of water.
Return the water to a full boil.
Process the jars for 25 minutes.
Remove the jars from the water bath and place them on a rack or towel-lined surface.
Allow the jars to cool undisturbed for 24 hours.
After cooling, check each lid to ensure it has sealed properly.
Store sealed jars in a cool, dark place.
Refrigerate any jars that do not seal and use them first.