Depending on the size of the mushrooms, cut them into 2 inches long by ½ inch wide pieces so they are all similar in size. This is a just a guideline - the idea is to have each piece cut to a similar size that can be easily eaten with chopsticks. Too big or too small is too hard to eat and therefore not good, plus they need to all cook in the same amount of time.
In a sauté pan, heat the olive oil over medium high heat until the oil starts to shimmer, add the garlic and cook until it becomes fragrant, then add the mushrooms and reduce the heat to medium. Cook for about one minute, season with salt and pepper and then add the vinegar, cover and cook for one more minute, shaking the pan frequently. Reduce heat to low and continue to cook for another minute, then turn off the heat and cool to room temperature. Once cool, serve and enjoy. Dust with the yuzu shichimi togarashi if desired.