base of ketchup (already has sugar, tomato vinegar - or you can do those individually) then more brown sugar and/or molasses, vinegar, bit of mustard, onion, garlic, soy, hot pepper, smoke flavor from liquid smoke, smoked paprika, or chipotles. sometimes instead of or in addition to the sugar we throw in a leftover jar of jam or fruit preserves nobody wants to finish.

can get quite hot and spicy, tangy and vinegary, or sweet and rich depending on proportions of stuff.

when I was young there was a group of old Arizona Pioneer families that met once year for a steak fry and there was a mustard based sauce that was so good, I wish I could find that recipe again. I know it was published in the paper once in the early 70s. I might have found it more recently, but didn't have subscription access to look at the old images.