Cut or tear a square of parchment bigger than the pot to be covered. Fold two opposite corners together to form a triangle, then fold this triangle in half into a smaller triangle; it will have two short sides and one long side. Position the triangle so that one of the short sides faces you. Fold this bottom edge up, making a narrow triangle, and crease it, maintaining the point of the triangle, as if you were making a paper airplane. Fold this “wing” over again, maintaining the point, and continue folding in this manner until you get to the other side—about five or six folds in all. You should finish with a very slender triangle.