I've always had success soaking my plank for a minimum of 45 minutes. I use a gas grill so I put the plank on the grill and turn all the burners on so the plank starts to put off a smokey aroma of the cedar (about 5 minutes). Then I turn off the burner that is directly under the plank, this method has never burned a plank. Place the marinated salmon directly on the plank - flesh side on the board, skin side up - this seals in the flavor much better. I immediately remove my plank from the grill and wash it as soon as it cools down. This method has allowed me to reuse the plank up to 4 times.
Yes, other planks can be used. There are hickory, alder, maple, cherry and probably others. Each has its own flavor. The more moisture a plank has the more it transfers to the meat, so things like pork chops and chicken will be moist and tender. So a couple of hours is best. It is possible to reuse the planks, if they are soaked for a long time, and the you cook them over low fire, but they do get charred. You can get ideas, recipes and planks at www.outdoorgourmet.com
I've soaked the plank (for a different recipe) for 30 minutes and had successful results. Nothing charred and the salmon tasted delicious. I don't think you need 4, but just soak it as long as you can... I personally wouldn't reuse a cedar plank just because some of the fish seems to stick to it--that just seems icky to me.
So which is correct? Do I soak the plank for (20) minutes as the recipe states or do I soak it for (4) hours as treemommax suggests? I too would like to know if the plank can be reused. My next question doesn't apply to this recipe. I have asked before but have not received an answer. How do I get to where the recipes are rated?
It's important to plan ahead for this - the plank needs to be soaked (immersed) for about 4 hours or the wood will catch fire; you won't get a nice, smoked fish, you'll get a charred one.
Can the cedar plank be used again or be thrown away? Can any other wood plank be used?
Oven method: Preheat oven to 350. Place the cedar plank on a rimmed baking sheet. Prepare the salmon as described above, then roast on the plank for 20-25 minutes.