Homemade Steak Sauce

yellow onion, chopped 2 cloves garlic, minced 1 cup Ketchup 1 medium sized lemon, juiced 1/4 cup Worcestershire Sauce 1/4 cup white wine vinegar 1/4 cup water 2 to 3 tablespoons tamari 2 tablespoons dark brown sugar 1 tablespoon (heaping) Dijon mustard