Accidentally bought a bag is poached peanuts instead of roasted. Can I roast them despite the fact that they are already cooked (and not raw)? If so, are there any extra steps I should take in doing so?
You can, just like you would for raw peanuts. However the boiled/poached peanuts have a bitter taste that is not removed by roasting and is generally unpleasant to eat as a snack. I would use these peanuts to make peanut sauces such as satay sauce, and possibly in other dishes where the peanuts are not the dominant flavor.