You could do a thick black bean soup with dollops of sour cream on top, with some sliced red peppers for garnish.
What about slices of dark brown bread (almost black) from a baguette that you slice (on the diagonal) and top with red tomato sauce & shredded mozzarella cheese that you can toast to get all melty.
A platter with dark purple grapes, strawberries, blackberries & dark figs would be yummy, maybe with some brie and white crackers. You could add white merangue cookies or dark chocolate candy too. Along similar lines, you could layer chunks of white angel food cake into a deep glass bowl, then add a layer of sliced strawberries, then white cool-whip, then blackberries, then white angel cake, and so on. Make a trifle out of it.