• Gather all the ingredients.
  

To make the dressing:

• Toast sesame seeds in a frying pan (without oil) until fragrant, about 3-5 minutes. Swirl and shake the pan once in a while for even toasting.  Transfer the toasted sesame seeds into your Japanese mortar and pestle. Grind the sesame seeds about half way (This adds texture to the dressing). If you don’t have a Japanese mortar and pestle, you can use a food processor or grind between your palms.
  
• Combine the rice vinegar, mirin, sugar, and soy sauce, then mix in the toasted sesame seeds.
  

To cut the ingredients:

• Remove the end of king oyster mushrooms and cut in half, about 2 inch (5 cm) long. Then cut it into slices.
  
• Discard the stems from the shiitake mushrooms and cut into thin slices.
  
• Cut off the bases of the enoki mushrooms, then separate with fingers.
  
• Cut the base of shimeji mushrooms and separate with hands.
  
• Discard the end of mizuna and cut the mizuna into pieces 2 inches (5 cm) long.
  

To cook the ingredients:

• Heat the oil in a large frying pan over medium heat. Add all the mushrooms.
  
• Sautee the mushrooms and add the kosher salt. Then add the sake and cook covered for 2 min over medium-low heat.
  
• Add the sesame dressing and toss to coat. Drizzle sesame oil and mix all together.
  
• Right before turning off the heat, add the mizuna and quickly toss all together. Remaining heat will continue to cook, so don’t worry about mizuna being still raw. Transfer to a serving dish and serve hot.
  

To Store

• You can keep the leftovers in an airtight container and store in the refrigerator for up to 3 days and in the freezer for 2 weeks.