How to Make It
Place shredded potato on a double layer of cheesecloth. Gather edges of cheesecloth together; squeeze cheesecloth to extract excess moisture. Place potato in a bowl.
Heat a large nonstick skillet over medium-high heat. Add pancetta; cook 4 minutes or until lightly browned and crisp. Stir in leek; cook 4 minutes or until tender. Add pancetta mixture, flour, sage, salt, pepper, and egg to potato; stir well to combine.
Return pan to medium-high heat. Add oil; swirl to coat. Add potato mixture to pan; flatten with a spatula into an even layer. Cook 12 minutes or until bottom is golden brown. Place a large plate upside down on top of pan; invert onto plate. Carefully slide potato cake into pan, browned side up; cook 10 minutes or until golden brown. Place potato cake on a cutting board; cool slightly. Cut into 8 wedges.