Is there a permit available, so an individual holding a steelhead or salmon tag could catch and then sell caught fish to local resturants?

Answer:

Yes and no.  Idaho code created a Commercial Steelhead Buyers license that allows an individual to buy and sell legally caught, hatchery produced, steelhead.  The same provision was not made for Chinook salmon.  Hence, yes - you can have a license to buy and sell steelhead but no there is not a license that allows the sale of Chinook salmon.