Wash the kale well and strip the leaves off of the stems. Slice across the leaves making 3/4 inch strips. Set aside.
In a large skillet, heat 1 tablespoon of olive oil over medium heat. Add the bacon, pepper flakes, and shallots. Cook over medium to low heat until the fat is rendered and the bacon in slightly brown and the shallots are golden.
Stir in the vinegar and brown sugar loosening and brown bits in the skillet.
Add the kale and toss to coat evenly.
Cook the kale until it is wilted and tender. This will take anywhere from 5 to 10 minutes depending on your tenderness preference.
Add salt and pepper to taste and transfer to a serving bowl.