Heat a large skillet or wok over medium heat, add oil. Add pancetta and cook, stirring occasionally, until golden brown and crispy, approximately 8-10 minutes. Remove to plate lined with a paper towel.

Add shallots to skillet and cook, stirring frequently, until golden brown, approximately 5 minutes. Add sage and cook approximately 1 minute. Remove shallots and sage, add to pancetta.

Add green beans to skillet and cook over medium-high heat, approximately 5 minutes. Season with salt and pepper. Add pancetta, shallots, and sage back to skillet and heat through, 2-3 minutes.

Turn off heat and add vinegar, toss well to combine.