If you need a substitute for umami pasta, your best options are liquid umami or tapenade with Parmesan cheese shakes. A simple combination of anchovy paste and tomato paste also works well. To bring its consistency closer to umami paste, mix a tablespoon of yeast with half a cup of olives, a clove of crushed garlic and a drizzle of olive oil. They're usually made with olives, anchovies and olive oil, the predominant flavors you'll taste in umami pasta.
If you want to add umami flavor to your food and are happy with a different flavor, truffle paste is an excellent option. In fact, any recipe that calls for umami paste will work just as well with a couple of teaspoons of this liquid. This is a good substitute for anyone who likes to experiment with new flavors, not for those who don't like surprises. Whether you're cooking one of Jamie Oliver's 5-ingredient recipes or something else that requires extra flavor, umami paste isn't really essential.
This is a recipe that mimics the Trader Joe's condiment mix and other umami spice blends available at many grocery stores.