If using fresh peas, bring a medium pot of water to a boil, add the peas and cook for 3 to 4 minutes, then drain them well. If using thawed frozen peas, skip this step.

Set a large skillet over medium heat and add the diced pancetta. Cook, stirring occasionally, until golden and crisp. Transfer the pancetta to a paper towel-lined plate, leaving the fat in the skillet.

Add the sliced shallots and red pepper flakes to the skillet. Cook over medium heat, stirring often, until the shallots soften, lowering the heat if they start to brown too quickly.

Add the peas and lemon juice to the skillet. Stir gently and cook just until warmed through. Season with kosher salt and freshly cracked black pepper to taste.

Transfer the mixture to a serving bowl, scatter the pancetta over the top, and finish with lemon zest. Serve warm.