A cartouche is a circle of greaseproof or parchment paper cut to the interior diameter of a pan and pressed gently onto the surface of a braising liquid. It reduces evaporation while still allowing a small amount of steam to escape, keeping the top surface of vegetables moist and ensuring even cooking throughout. Without a cartouche, the upper surface of braised vegetables can become dry and fibrous while the submerged portion is tender. To make one: fold a square of greaseproof paper in half twice to form a smaller square, then fold diagonally into a triangle. Hold the tip of the triangle over the centre of the pan and trim the outer edge to match the pan's radius. Unfold — you have a rough circle. Press it gently onto the surface of the liquid before braising.