Place the bacon in cold 12-inch skillet. Heat the pan over medium heat and cook until the bacon is crispy and the fat is rendered. Once crispy, set aside on a paper-towel-lined plate. To the leftover bacon fat, add the red pepper and cook until softened, 5 to 7 minutes.
Stack the leaves of collards and roll tightly into a cigar shape. Then chop away.
Add the collards to the pan along with the apple cider vinegar, red pepper flakes and some salt and pepper and cook until tender, but still bright green, 4 to 5 minutes. Adjust the seasoning if necessary. Toss with the reserved crispy bacon and serve.