Heat large heavy skillet over medium flame. Add oil and heat for a few seconds. Add onion, stirring frequently until softened and translucent, about 7 minutes. Add beets, turnip, and carrot and stir to coat about 1 minute. Add greens (if skillet is too small to fit all greens at once, add a portion at a time and allow them to wilt a bit before adding more). Stir greens to coat in oil and vegetable mixture. Add garlic, water, tamari, and mirin or wine. Stir to combine; cover for 5 minutes, or until greens are wilted but still retain bright green color. Remove from heat and toss with ume plum vinegar. Season to taste with salt and pepper and serve immediately.