2tspRed Pepper Flakesadjust if you prefer more or less spice
1cupWhite Wine Vinegar
Pulse bell peppers with red-pepper flakes in a food processor until finely chopped.
Combine peppers, vinegar, butter, salt, and sugar in a 5- to 6-quart heavy pot. Bring to a vigorous boil over high heat. Continue to boil until mixture reduces slightly, about 20 minutes. (The longer it cooks, the thicker the jelly will be, but 20 minutes produces the right consistency for me.)
Pour the jelly into containers and refrigerate or freeze until ready to use.