To paint over ANY surface, without sanding, use a product called 'ESP Easy Surface Prep', available at hardware and paint shops. Wipe on, wipe off and paint in 90 minutes. Works well over enamel paint , without having to sand. SAVES HOURS of work. It was recommended to me by a professional painter.
This is a great way to create an outdoor kitchen on the cheap. I'd estimate it would cost us about $200 to recreate this for our space (with one extra side visible since we don't have a corner like this) - stone veneer, plywood, and stain and concrete for countertops (which I would prefer over the granite in the photo).