Wash the greens and remove any thick stems. Give them a couple of good chops. I didn't do this and I regretted it as the leaves do get slightly chewy and hard to cut once cooked.
1 bunch of mustard greens
Heat a non-stick skillet over medium-high heat and fry the bacon until nice and crisp. Remove and set aside on a paper towel to dry.
1 slice of bacon
Add the cut mustard greens to the skillet tossing with the bacon fat. They will almost immediately begin to wilt. Sprinkle with a little kosher salt and a splash of vinegar.
Kosher salt, 1 tablespoon balsamic vinegar
Remove the greens once they wilt to your desired doneness. It won't take long. -- 2-3 minutes max.
Chop the cooked bacon.
Top the greens with feta cheese, pecans and bacon.