You must either get the flavorings inside the peanuts, or on the surface of the raw peanuts.
What flavors are you interested in adding?
Aromatic flavors like garlic, star anise, cloves, ginger, or raw vanilla beans may transfer to peanuts if your store the raw dried peanuts mixed with the dry spices for several days to weeks.
Another method is to wet the peanuts' surface with water or oil, and sprinkle them with: cayenne, paprika, cumin, powdered garlic, fine salt, ground pepper, curry powder, allspice, powdered ginger, Chinese 5 spice, cinnamon and sugar, cumin, onion powder, honey, soy sauce, Tabasco, Italian seasoning, lemon pepper, Sriracha, Cajun seasoning, Parmesan, or other finely ground spices, flavorings, or liquid seasonings.
Then dry the raw peanuts in the oven for a few minutes. Drying the spiced raw peanuts in the oven should take just a few minutes at 250 degrees Fahrenheit, not nearly enough to roast them (which takes about 25 to 30 minutes at 320 degrees F), but enough to cause the spices to stick to the outside of the raw peanuts.
