Hoisin sauce is a unique flavor, due to the combination of salty, sweet, and umami. The rich and thick texture also sets it apart from other sauces. However, that doesn’t mean it’s impossible to replace. The best way to find something that tastes like hoisin sauce is to play around. Hoisin is sometimes considered Chinese barbecue sauce, so American barbecue sauce is a good place to start. This has the same blend of sweet and salty. Adding molasses will give it depth, soy brings umami, and Chinese 5-spice will add some authenticity. If you can find black bean sauce, then this is a similar base flavor to hoisin. With the addition of soy sauce, sugar, and rice wine vinegar, it becomes layered. Oyster sauce has a similar, if thinner consistency, and the same umami profile as hoisin. Use a little, and sweeten with brown sugar.