Sautéed Swiss Chard with Pancetta and Caramelized Shallots | America's Test Kitchen

Ingredients

• 2 tablespoons vegetable oil
• 3 shallots , sliced thin
• 2 ounces pancetta , cut into 1/4-inch pieces
• 1 1/2 pounds Swiss chard , stems sliced 1/4 inch thick on bias (3 cups), leaves sliced into 1/2-inch-wide strips (10 cups)
• 1/4 teaspoon kosher salt
• 1/8 teaspoon red pepper flakes
• 1 tablespoon balsamic vinegar