In a small bowl combine the marinade ingredients and mix well. Spread the marinade evenly over the flesh side of the salmon, then wrap the salmon in plastic wrap and refrigerate for at least 1 to 2 hours or preferably overnight.
Soak the cedar plank in water for at least 1 hour.
Prepare the grill for indirect cooking over low heat (250° to 300°F).
Prepare the grill for cooking over low heat (275°F).
Drain the cedar plank and place it on the grill over indirect heat. Unwrap the salmon and place it, skin side down, on the plank. Grill the salmon over indirect low heat, with the lid closed, until an instant-read thermometer inserted into the thickest part of the salmon registers 135°F, about 1 hour.
Drain the cedar plank and place it on the grill over indirect heat. Unwrap the salmon and place it, skin side down, on the plank. Grill the salmon over low heat, with the lid closed, until an instant-read thermometer inserted into the thickest part of the salmon registers 135°F, about 1 hour.
Meanwhile, make the salsa. In a medium bowl combine the tomatoes, avocado, cucumber, scallions, chile, dill, oil, and vinegar and stir gently to mix well. Season to taste with salt and pepper and with a little sugar if needed.
Bring a medium saucepan of salted water to a boil on the stove and add the potatoes. Cook until tender, about 15 minutes. The timing will depend on the size of the potatoes; pierce with a fork to test for doneness. Drain and transfer to a bowl. Add the oil, season with salt and pepper, and toss to coat. Keep warm until serving.
Transfer the salmon to a serving platter and accompany with the salsa and potatoes. Serve with lemon wedges for squeezing over the fish.
