1medium onionfinely chopped (use a small onion if you prefer less in the stuffing)
1/4cupchopped fresh parsley OR 2 tbs dehydrated parsley
Preheat oven to 350℉. Place a rack in a large baking/roasting pan (I use a flat rack).
Prepare pork as follows; If using a boneless loin, cut it in half lengthwise and pound it down to 1/2-inch thickness. Pork tenderloins generally come in 2 pieces so pound each piece down to 1/2-inch thickness.
Mix breadcrumbs, poultry seasoning, parsley, salt and pepper together in a large bowl; set aside.
Melt butter in a small skillet. Add the onions and cook over medium-low heat until they are translucent—don’t let them brown.
Add the entire contents of the skillet to the breadcrumb mixture and mix well until all the bread is coated with the onions/butter mixture.
Divide the stuffing evenly between the 2 pork pieces. Roll up from the short side tightly, forming a “jellyroll.” Secure seam with toothpicks.
Place on the rack in the pan and baste with half the butter.
Bake for 90 minutes, basting again with the melted butter halfway during the cooking, or until the meat registers 160℉ on a meat thermometer.
I make soft breadcrumbs by tearing apart plain old white bread and processing it to fine crumbs in my food processor.