Bring the water to a boil and add the salt. Add the oats, reduce the heat and cook for 10 to 20 minutes, to desired consistency. While the oats are cooking, warm the sesame oil in a skillet. Add the mushrooms and ginger and sauté for one minute. Add the tamari and red pepper flakes, and cook until the mushrooms are nice and brown, about 3 minutes. Turn off the heat, add the spinach, and mix well.
Transfer the oats to a bowl, top with the mushroom and spinach mixture and some plums. Bon appétit!