Right now, it's red chili sauce and brown sugar in a 1-to-1 ratio and an optional pinch of instant coffee. I use it as an all-around dipping sauce but it can work as a sandwich spread and cracker dip as well. The chili sauce is quite hot and spicy and the sugar sorts of mellows it out. That bit instant coffee adds a bit of complexity that I can't really pinpoint.

Prior to that, my usual go-to is a 1-to-1-to-1 ratio of soy sauce, vinegar and brown sugar in a poor imitation of kecap manis and vinegar. I usually use it for fried fish but it also goes well with other fried meats (chicken, porkchops, etc). The brown sugar goes well with soy sauce and the vinegar (especially spiced vinegar that are commonly available where I live) gives it a kick that counteracts the richness and grease of fried meats.