Weber Tangy Barbecue Sauce

2 T. butter
3 T. chopped onion
1/2 c. chopped celery
2 T. sugar
1 T. Worcestershire sauce
2 T. vinegar
1/4 c. lemon juice
1. c ketchup
1 t. dry mustard
dash of pepper
melt butter in a skillet and cook onion and celery until tender. Add the remaining. and cook to blend favors, makes 1 2/3 cups.