If using fresh peas, bring a medium pot of water to boil. Blanch the peas for 3-4 minutes and remove. If using frozen peas, skip this first step.
Heat a large skillet over medium heat. Add the pancetta and cook until golden brown and the fat has rendered. Remove the pancetta to a plate lined with paper towels.
Add the shallots and red pepper flakes to the pan and cook until soft. Add the peas and cook until warmed through. Transfer to a large bowl and top with the crisp pancetta and lemon zest.