Wash greens well, remove stems, and tear into large pieces. Drain well, leaving the greens slightly moist.
Melt duck fat in large pot, add greens, and cover pot. Cook stirring often until greens have mostly wilted, then check to make sure there is enough moisure in the pot to keep the greens from burning.
Let greens cook covered until they are completely wilted and tender, but still have a dark green color. Add salt and pepper and white balsamic vinegar. Stir well, and serve.
Note: I do not use collards or kale in this recipe because they need a longer cooking time. I use as many different kinds of greens as I can, including turnip, beet, bietola, chard. nettles, horseradish, and even a few radish greens if they look nice and tender.
If you don't have truffled duck fat, plain duck fat or goose fat are both delicious.