Between the politicos and law partners, Beacon Hill needs a strong power lunching spot in the shadow of the State House’s golden dome. Since 2007, Mooo…. has answered that call. The steakhouse sibling in chef Jamie Mammano’s family of restaurants (which includes Mistral, among others) has the top chops and impressive environs that open wallets and close deals. And the private wine-cellar room, with dramatic vaulted ceilings, is fit for wooing a whole herd.