Start by cleaning the button mushrooms thoroughly with a damp cloth to remove any dirt. For larger mushrooms, halve them to ensure they cook evenly.

Heat a large sauté pan over medium heat and add a drizzle of oil. Allow the oil to shimmer for a minute before adding the mushrooms. Sauté for 10–15 minutes, stirring frequently, until mushrooms release their moisture and turn a lovely golden brown.

Reduce the heat slightly and add the miso paste, butter, and minced garlic to the pan. Stir them in well and let the mixture cook for about 3 minutes.

Once the garlic is fragrant, remove the pan from heat. Drizzle in the rice vinegar, stirring gently to deglaze the pan and scrape up any browned bits.