Heat the oil in a wide skillet or stir-fry pan. Add the seitan and sausage and sauté over medium-low heat until golden-brown on most sides, stirring frequently.
Stir in the garlic and continue to sauté until golden, stirring frequently.
Meanwhile, trim the stems and midribs from the greens, rinse well, and chop. Add the greens and wine to the skillet (if using kale, add water as needed to keep the skillet moist).
Cover and cook 5 to 7 minutes for the chard and 6 to 8 minutes for the kale, or until the greens are cooked to your liking. Stir occasionally and don't overcook!
Add the spinach, cover, and cook briefly until wilted, then uncover and cook for another minute or so. Season with salt, pepper, and red pepper flakes, then serve.