In a saucepan cook onions in oil over moderate heat until tender.

Stir in garlic, red pepper flakes, and chili powder and cook for one minute.

Add chili sauce, beer, vinegar, water,brown sugar, mustard, Worcestershire sauce, salt, black pepper, and Tabasco sauce, stiring to combine.

Partially cover and simmer until slightly thickened about 15 to 29 minutes.

Taste and adjust seasoning, if necessary with Tabasco sauce.

Remove sauce from heat and allow to cool completely.

Sauce can be refrigerated for 2 to 3 weeks or frozen for up to a month.