"Cutting in" means working a solid fat into a flour mixture with a pastry blender (or two knives) until the fat is evenly distributed in little crumbs with a few larger, pea-sized pieces. The smaller crumbs act as a tenderizer for your dough and the larger pieces are what make the pastry flaky. Here's how flakes work... After you add liquid to the fat/flour mixture to create a dough, the little pieces of fat stay in little pockets within the dough. When the dough hits the heat of your oven, the fat pockets quickly melt and leave little empty spaces in their place. These layers of dough and air pockets are what create a flaky effect. See those layers of dough and fat? Flake City! Here's how you "cut in": Press your pastry blender into the fat/flour, and twist your wrist as you do it, in sort of a grinding motion. Be sure to scrape off the blades of your pastry blender in between cuts so the fat doesn't build up on them. If you don't have a pastry cutter, you can use two knives (below). Just cut away until you get the desired size of chunk. What you're aiming for is a mixture with a variety of crumbs in it -- from nearly indistinguishable to pea-size. I even like to leave in a couple that are a little bigger than a pea. If your mixture is mostly ready with a big old hunk left in it, just squish the hunk between your fingers, rather than over-cut your fat. Here are some more tips for cutting in fat to make the flakiest pastry: * Start with ice cold fat. The colder the fat, the more your fat will stay in little crumbs, rather than creating a floury paste. * Use a pastry blender if you have it, for the best results, or two knives in a pinch. A pastry blender is just much more efficient. *  If your pastry calls for both lard (or shortening) and butter, start with the lard first, then cut in the butter. Cold butter is firmer than cold lard, so when creating a mixture of tiny crumbs and larger pieces, it makes sense to start with the lard -- which will break down into smaller bits, anyway -- to tenderize the dough, then use butter to create flakes! * I also take an extra step to ensure the fat pockets are nice and cold. I will often refrigerate my dough and fat mixture for 10 minutes before adding the liquid. It just re-hardens the chunks and fortifies them before you shape your dough, so you get the flakiest possible effect. To see how to measure lard properly, click here! Photography: Annabelle Waugh