If you don't have store-bought mushroom broth but still want great flavor, try this easy vegan dashi (i.e., Japanese soup stock). 1. Snip 1 piece (5g) of kombu with scissors in a few places. Add to a large glass or measuring cup along with 3 dried shiitake mushrooms (9 to 10g). Pour 1 1/2 cups (180 mL) water on top and place a small bowl on top to keep the mushrooms submerged. 2. Soak for 30 minutes (or for several hours), while you prep the other ingredients. 3. Set a fine mesh sieve over a bowl. Strain the liquid to catch any sediment, reserving the stock. Remove the kombu and discard, but you can save the mushrooms (rinse them several times until the sediment is gone). 4. Add the stock and rehydrated mushrooms to the blender when you blend up the broth.