In a medium saucepan over medium-high heat, combine the sugar, onion powder, kosher salt, celery seeds, garlic powder, chili powder, pepper, cumin, cayenne, ketchup, vinegar, mustard, lemon juice and liquid smoke. Cook, stirring, until boiling. Reduce heat to simmering and cook, stirring occasionally, 25 minutes or until mixture is thickened to your liking. Whisk in butter until incorporated into the sauce. Let cool slightly before using.The sauce can be used immediately or covered tightly and refrigerated up to 2 weeks or frozen up to 3 months.
A 2 tablespoon bbq sauce per serving is used in my calculations.