Roughly chop the garlic in a food processor fitted with the metal blade. Add the capers and process until they are finely chopped. Add the olives, bell peppers, and basil and pulse a few times to coarsely chop them. Pour in the oil, and pulse until the mixture is just blended, but not perfectly smooth. Transfer the mixture to a bowl and serve it with baguette slices or crackers. (If made ahead, cover and refrigerate the tapenade for up to 3 days.)