Hand wash with a gentle detergent, do not use steel wool or scouring pads as they will scratch wood; dry immediately with a soft cloth.
Do not soak or leave unwashed overnight.
Mineral oil can be used to restore richness of the wood color- apply with a soft cloth, let stand one hour and wipe away excess with a gentle detergent, dry immediately.
Note - as with all marble, wine or rich colored foods may stain the naturally porous material.