The elegance of a neatly stuffed pork roast belies its simplicity. Not that a well-marbled pork sirloin needs flavorful embellishment -- its fat and meatiness have flavor covered -- but stuffing it with a savory or sweet filling isn't gilding the lily, either; the filling contributes more than aesthetics. A thoughtful stuffing ties the pork into its side dishes, adds texture and elevates the flavor, complementing and contrasting the lean meat embracing it.
Prepare the stuffing 2 to 24 hours before you cook the sirloin. Preparing the stuffing early gives the ingredients time to marry and meld flavors. The stuffing ingredients determine your optimal make-ahead time.
**Bread Stuffing** Make bread stuffing **without mixing the wet and dry ingredients** up to 24 hours ahead of cooking. For example, if you want a [classic bread stuffing](http://www.ehow.com/ehow-food/blog/moms-classic-make-ahead-bread-stuffing/) , saute the vegetables and aromatics with herbs and spices and store them overnight in the refrigerator. Add the binder -- stock, milk and/or eggs -- and the bread just before you stuff the pork.
**Meat Stuffing** Marinate meat-based stuffing overnight, and fully cook it the next day. You have to cook meat stuffing twice -- before you stuff the pork and after you stuff the pork -- to 165 degrees Fahrenheit. Let meat-based stuffing cool before you fill the pork with it.
- **Grains, Herb, Fruit and Vegetable Stuffing** Partially cook grain and vegetable stuffing with herbs and spices the day before. Consider cooking vegetables _[a la Grecque](http://www.foodandwine.com/recipes/vegetables-a-la-grecque)_, a French technique that combines par-cooking and marinating, for added plumpness and a boisterous flavor.
Readying a pork roast for stuffing couldn't be much easier, unless you use one of the most neglected meat-preparation techniques of all -- asking your butcher. Butchers and meat cutters are often more than obliged to butterfly pork sirloin upon request and not hesitant to offer a few cooking tips as well.
To butterfly the pork sirloin at home, position it fat-side down and slice it lengthwise down the center until it opens like a book -- leave about 1/2 inch of meat connecting the halves. If the roast has a thick layer of fat along the top, known as a fat cap, trim it to about 1/4 inch thick.
Stuffing and Tying
You need about 1 cup of stuffing per 1 pound of pork. Add finishing ingredients -- freshly chopped herbs, kosher salt and garnishes -- to the stuffing and give it a final mix. If moisture collected during the wait, drain it for several minutes.
Heat the oven to 450 F. Open the pork loin, and season it on both sides with kosher salt and fresh pepper. Coat both sides with oil, and place it fat-side down on the work surface.
Spoon the stuffing lengthwise down the center of the pork sirloin. Roll the sirloin roast around the stuffing and tie it at 1-inch intervals with twine. Set the stuffed pork in a shallow baking dish.
Roast stuffed pork sirloin for 15 minutes at 450 F, and then lower the oven temperature to 400 F. Roast the stuffed pork until the center reaches 165 F, and take it out of the oven.
Transfer the stuffed pork sirloin to a cutting board. Use the drippings to make a pan sauce while the pork rests for 10 minutes. Untie the pork roast and slice it crosswise into 1/2- to 3/4-inch pieces.