*If you can’t find Porcini mushroom powder, simply grind dried Porcini mushrooms (about 3/4 ounces) in a coffee or spice grinder until they are powder.
Grind dried Porcini Mushrooms in a Coffee or Spice Grinder for powder
In a small bowl, combine the sugar, salt, black pepper, red pepper flakes, mushroom powder, garlic, and olive oil. Stir well to form a thick paste. Mix it up, and slather it on! Rub the paste all over the roast, coating it evenly.
Wrap it tightly in plastic wrap and refrigerate for at least 12 hours (ours only managed about 5 hours).