Add the water and veggie broth. Then add the kombu and mushrooms. Bring the broth to a boil, but right before it boils, remove the kombu (apparently boiling kombu can make it slimey). Once boiling, bring the heat down to a simmer and put the lid on, slighly tilted. Cook for 20-30 minutes to enhance the flavors. This broth will be very light and not salty, to allow for the miso that will go in later.