In a large deep pot or skillet with a cover, cook bacon until fat is rendered, 4-6 minutes. Add onions and additional oil and cook until soft, 8-10 minutes. Add in the garlic. Sauté 3-5 of minutes, stirring frequently. Add greens to pan with 1/2 cup water.
Cover pan and steam for 5 minutes.
Uncover, stir constantly until greens shrink. Add salt and pepper and continue to cook until greens are tender.
Sprinkle cider vinegar on mixture. Cover.
Turn off heat. Let stand until ready to serve.