Soak the shiitake and kelp in water for 1 hour.
Add the ingredients with water to a pot, heat it up over medium-low heat, when it starts to simmer, let it cook for 10 mins
Take the kelp and shiitake out, turn off the heat. Add soy sauce, vegan oyster sauce and yeast extract paste.
Wait for it to cool down then store it in air-tight bottles, it can be kept in the fridge for 2 weeks.