Talented young chef Luca Ludovici is serving “sub-zero kilometer” cuisine with ingredients aged underground.ConTatto RistoranteCredit: Photo by Ivan SommonteAt ConTatto Ristorante, a gourmet restaurant in Frascati, Italy — one of the little, hilltop towns that make up the Castelli Romani near Rome — dinner begins in an underground cave. That’s where chef Luca Ludovici, who runs the restaurant with his wife Lorena Cavana, serves the amuse bouche,…