Grilled Salmon with Potato and Watercress Salad

INGREDIENTS

• 3 pounds small (each about 2 in. wide) red thin-skinned potatoes
• 1 cup thinly sliced red onion
• 1 cup seasoned rice vinegar
• About 1/2 pound watercress, rinsed and crisped
• 1 salmon fillet, about 2 pounds
• 1 tablespoon soy sauce
• 1 tablespoon firmly packed brown sugar
• 2 cups alder or mesquite wood chips, soaked in water
• Salt