We need to obtain a thin, rectangular piece of meat from the turkey breast. If you've purchased whole turkey breast, you need to remove the bone, the skin and the tenderloin (leave the tenderloin if it's small and well attached to the rest of the breast). It's best to buy a piece of turkey breast that is more square-shaped than triangular (only if you can choose, both types will work). Place the turkey breast on a large chopping board, skin-side down (but skin needs to be removed prior to this step). Now butterfly the turkey breast: you need to cut parallel to the chopping board, cut along the length of the breast, but not all the way through, then open the breast like a book. At this point, you can repeat that on the left and right side of the meat if it's too thick to pound. I found out that rather flat and smaller turkey breasts allow that you butterfly them only once, but bigger pieces of meat require double butterflying (you can also butterfly the meat only once and just pound it a little more). When you're ready with cutting the meat, place a thick plastic foil or baking paper over the meat (to avoid tearing the meaand pound it with a meat mallet to an even thickness of 1/2-3/4-inch / 1,5 cm. The meat should be more rectangular than square, but it should not be a long rectangle. All shapes will work but bear in mind that a square-shaped piece of meat will make thicker (talleroulade which needs to be baked longer.