A spice mixture of toasted peppercorns, coriander, garlic, shallots, and sage flavors a pork shoulder that's perfectly succulent after slow, tenderizing cooking.
Toast peppercorns and coriander seeds in a small saute pan over medium-low heat until fragrant, about 5 minutes. Let cool completely. Transfer to a food processor. Add garlic, shallots, sage, and 1 tablespoon salt, and grind to a chunky paste. With processor running, slowly add oil; mix until well combined.
Untie pork, if tied. Rub pork with spice mixture. Put in a resealable plastic bag, and expel air; seal bag. Marinate in the refrigerator, turning occasionally, overnight or up to 3 days. Let stand at room temperature 1 to 2 hours before cooking.
Preheat oven to 450 degrees. Roll pork, and tie into a compact log with kitchen twine. Transfer to a small roasting or medium baking pan. Roast 20 minutes. Reduce oven temperature to 350 degrees; continue to cook until an instant-read thermometer inserted into the thickest part registers 150 degrees, about 2 hours 15 minutes. Transfer to a warmed platter, cover with foil, and let rest 10 to 15 minutes before slicing.