Dice the uncooked bacon.
In a high-sided skillet, cook the bacon over medium heat until brown, about 5 minutes.
In the same pan add the onions and sauté until translucent, about 5 minutes.
Strip the leaves from the tough stems of the collard greens. Stack the leaves, roll them up and cut them into thin strips.
Add the greens to the skillet with the bacon and onions. Add the garlic and red pepper flakes, brown sugar, cider vinegar, salt and pepper, to taste.
Stir and cover the skillet. Cook for 15 minutes, stirring halfway though.
Collards are done when tender and no longer bitter.