Destem the kale and slice leaves into ½ inch strips. Set aside.
Heat a large skillet or wok over medium heat, add oil. Add pancetta and cook, stirring occasionally, until light brown approximately 4-5 minutes.
Add garlic, red pepper flakes, and salt and cook, stirring, about 30 seconds.
Add kale and cook, stirring occasionally, until kale is cooked and pancetta is crisp, approximately 5 minutes.
Add lemon juice and zest, toss.