Northern Oak Planks: Soak the planks in water for approximately two hours to rehydrate the sap in the plank. Lightly coat plank with olive oil. Marinate catfish fillets for one half hour in a lemon, wine, dry mustard, and fresh cilantro solution using only one half of your marinade. Place the catfish fillets on the plank on a cookie sheet on the grill or under your oven broiler element. Baste the fillets with remaining marinade for about five minutes per side. Add garnish and serve on the oak plank!