Preheat gas or charcoal grill to medium-low heat or 350°F. Rub salmon with oil and season with Classic Rub; set aside.
In a large mixing bowl, combine cucumber and onion. Top with yogurt, lemon juice, garlic, mint, and salt. Fold into cucumber mixture and season with freshly ground black pepper to taste. Set aside while salmon is cooking.
Place soaked plank on grill, close lid and heat for 3 minutes. Flip plank and place salmon on heated side of plank. Close lid and cook for 10-15 minutes, depending on thickness of salmon. Remove from grill when salmon is medium-rare or medium-well (fish will continue to cook after removing from grill). Serve with Cucumber-Yogurt sauce.