You can use either Miso & Easy (ready made miso in convenient bottle) or regular miso paste that you can find at grocery stores (usually in refrigerated section near tofu) or health food stores (like Whole Foods).
Ingredients:2 pounds red potatoes, scrubbed
2 tablespoons butter
2 tablespoons Miso & Easy (or 1 tablespoon regular miso paste)
2 tablespoons milk
2 teaspoons minced fresh chives, parsley or green onion
In a large pot, add the potatoes and cover with water by 2 inches. Bring to a boil, then turn heat to medium and let cook for 20 minutes, or until the potatoes are easily pierced with a fork.
Drain the water, leaving the potatoes in the pot. Mash the potatoes with a potato masher. Add in the remaining ingredients and mix well. Taste and season with additional miso (needs more flavor) or milk (too thick) if needed.