Roasting. 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.oasting. 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.