Time: 45 minutes, plus 2 hours to soak plank
1. Put 8 cups hot water and table salt in a pan big enough to hold the plank; stir to dissolve salt. Soak plank at least 2 hours.
2. Meanwhile, prepare a charcoal or gas grill for indirect medium-high heat.
3. Wipe water off plank and rub it with 1 tsp. oil. Set it over direct heat and toast it, covered, until it starts to smoke and char, 5 to 10 minutes.
4. Meanwhile, season salmon fillet with kosher or sea salt and pepper. Turn plank over, set over indirect heat, and set fillet, skin side down, on charred side. Dot with butter.
5. Close lid on grill and cook salmon until center of fillet flakes, 30 to 40 minutes.
Quick tip: Look for (or ask for) a long, narrow fillet that fits your board. If all you can find is a short, wide fillet, just divide it down the center and lay the pieces end to end on the board to fit.
Per serving: 322 cal., 55% (176 cal.) from fat; 34 g protein; 20 g fat (4.3 g sat.); 0.1 g carbo (0 g fiber); 258 mg sodium; 98 mg chol.