The guys behind the counter at Katz’s Deli were whipping up something a little different yesterday. It’s a gargantuan new creation made with roast beef, turkey, salami, coleslaw and the legendary deli’s own version of Russian dressing. The sandwich, dubbed the “Roast Beast,” is a promotion for Dr. Seuss’ “How the Grinch Stole Christmas! The Musical,” opening December 5 at Madison Square Garden. It will be offered November 17 to December 28 for $22 plus tax. We know, not cheap, but this monster could probably serve the whole family, or at least a couple of people. [In case you’re curious, a regular roast beef sandwich at Katz’s costs $17.95]. By the way, the MSG team is offering special discounted tickets (up to 30% off on selected performances) for the theatrical production. You need to use the code KATZ. Here’s the link.