Makes about 1 cup
Stir together ketchup, vinegar, Dijon mustard, shallot, brown sugar, and dried crushed red pepper in a medium saucepan. Bring to a boil over medium heat; reduce heat to low, and simmer, stirring occasionally, 8 to 10 minutes or until thickened. Season with kosher salt and freshly ground black pepper. Refrigerate in an airtight container up to 2 weeks.