Ingredients
Peppers: 36 to 40 medium banana peppers (or a mix of bell peppers and jalapeños for more heat)
Sugar: 6 cups granulated sugar
Mustard: 1 quart prepared yellow mustard
Vinegar: 1 quart cider vinegar
Flour: 1 1/4 cups all-purpose flour
Water: 1 1/2 cups cold water (plus more for boiling)
Salt: 1 teaspoon salt
Instructions
Prep and Chop the Peppers: Wearing gloves, remove the stems and seeds from your peppers. Finely grind or blend the peppers in a food processor. I prefer to hand chop some. I like it a lil chunky.
Boil the Mixture: In a large pot, combine the blended peppers, sugar, yellow mustard, cider vinegar, and salt. Bring the mixture to a rolling boil and let it cook for 10 to 15 minutes, stirring frequently.
Thicken the Butter: In a small bowl, whisk the flour and cold water together until completely smooth with no lumps. Slowly stir this flour paste into the boiling pepper mixture.
Final Simmer: Continue to boil and stir the mixture for another 5 minutes, or until the sauce thickens and the flour taste is cooked off.
Can or Store: Ladle the hot pepper butter into sterile glass jars, leaving about a 1/2-inch of headspace, and process in a boiling hot water bath for 10 minutes. If you aren't canning, let it cool and store it in your refrigerator.