When I'm making a recipe that calls for roasted peanuts, I generally just want 'peanut'. Not 'salted' or sprinkled with Riboflavoxide or anything else. Also, it lets you fake crunchy peanut butter if all you have is smooth! And they taste great fresh.
Step 1: Raw Deal
Preheat the oven to 350 degrees F (177 C).
I prefer to start with raw peanuts that have been blanched to remove their skins. You can do this recipe just fine with the skins still on, but it's much messier, and I generally don't want peanut skin in my marinade.
The best deal I've found on them is at my local Asian grocery.
Line a sheet pan with aluminum foil, and spread the nuts out into an even layer. Put on a middle rack in the oven.
I set the timer for 18 minutes, and then start checking them every minute. The ones in the picture went 22 minutes.
There is a fine, thin line between 'toasted' and 'toast.'
After you do a few batches, your nose will be able to tell you when they're done -- they smell fabulous.
Step 2: All Done
If you are planning on eating these as a snack, and want to salt them, there is never going to be a better time to do so than right when they come out of the oven.
Let cool, then store in an airtight container.