Soak corn in a large bowl of cold water for 20 minutes.
Remove and pat dry. Coat corn on all sides with cooking spray, and season with 1/4 teaspoon salt and 1/4 teaspoon pepper. Grill about 15 minutes or until charred on all sides.
Remove cobs from grill, and cool slightly. Slice the kernels from the cobs, and transfer to a medium bowl.
Add tomatoes, olive oil, vinegar, and sliced basil; season with 1/4 teaspoon salt and 1/4 teaspoon pepper.
Let the relish sit at room temperature for 15 minutes before serving.
Meanwhile, lightly coat both sides of salmon fillets with cooking spray; season with remaining 1/4 teaspoon salt and 1/4 teaspoon pepper.
Place fillets skin side down, and grill 34 minutes or until golden brown. Flip fillets, and grill for 3 more minutes. Fish should feel slightly firm in the center and will register 145 on an instant-read thermometer.
Place salmon onto each of 4 plates, and spoon relish over top.
