In a food processor or blender, combine olives, roasted red sweet peppers, garlic and black pepper. Cover and blend or process until nearly smooth, scraping down sides of container as necessary. (For make-ahead, tapenade can be stored in an airtight container in refrigerator for up to 1 week.)
Split focaccia in half horizontally. Brush olive oil evenly on each side of each bread half. For a charcoal grill, grill bread halves on the rack of an uncovered grill directly over medium-hot coals about 2 minutes per side or until grill marks form and bread is browned and crisp. (For a gas grill, preheat grill. Reduce heat to medium-high. Place bread halves on grill rack. Cover and grill as above.) Remove from grill. Cut into 1-1/2-inch pieces (canapés).
To serve, place the focaccia canapes onto a large serving platter and spoon equal amounts of the tapenade onto each piece. Sprinkle with basil. Makes 16 to 20 servings.