Cutting boards with cutouts: a small alteration that helps guide food into/onto a prep bowl or plate. One of these boards might just fit your sink, but check to make sure your undermount has a minimum of 1/2″ reveal. Elkay has a whole range of sinks and accessories, so if neither of these fit your specifications, you might check out their other offerings.
Elkay 16″ x 8″ Hardwood Cutting Board, $46.72
Dimensions: 16-3/4″ x 8-1/2″
Elkay 16.75″ x 15″ Hardwood Cutting Board, $55.68
Dimensions: 16.75″L x 15″W x .75″H