Sprinkle salmon fillets evenly with salt and pepper; set aside.
Snip off any protruding stems from grape leaves. Place 2 or 3 overlapping grape leaves on work surface. Place one salmon fillet, skin-side down, in center of leaves. Fold grape leaves up and over salmon, patting down gently to seal as much as possible. Brush leaves with olive oil to help seal edges. Repeat with remaining salmon and grape leaves.
Grill packets, covered with grill lid, over medium heat (300° to 350°) 5 to 6 minutes on each side or until desired degree of doneness. (Grape leaves will be lightly charred.) Serve immediately with Tomato-Raisin Relish.