Grilling Sauce

A traditional grilling sauce.

1/4 cup butter
1 medium onion, diced
1/4 cup yellow mustard – regular ballpark
1/4 cup water
Juice of 2 lemons
2 Tbsp. ketchup-style chili sauce
1 Tbsp. white or rice vinegar
1/4 tsp. cayenne pepper
1/2 tsp. kosher salt

In a saucepan that is nonreactive, melt the butter over medium heat. Add the diced onion and cook for 10 minutes. Add all of the rest of the ingredients, reduce heat to low and cook for 15 more minutes. Serve warm.