Four-Citrus Salsa

Using a sharp knife, peel the orange, grapefruit, lemon and lime, removing all of the white pith. Working over a strainer set over a bowl, cut in between the membranes and release the citrus sections into the strainer. Squeeze the membranes over the bowl to extract as much of the juice as possible. Whisk the olive oil and tapenade into the juice. Cut the citrus sections into 1/2-inch pieces and add them to the dressing, along with the red onion and parsley. Season with salt and pepper.