How can you maximize umami?

When cooking a soup, you might put ingredients after the water is boiled, but Hokto mushrooms increase in umami best at 60-70℃ (140-158℉) that they should be put in a pot when the water is warm or even cold to go through the temperature range.  Another point is you should not overcook.  Furthermore, by combining different Hokto mushroom species, you can multiply and deepen the umami.