Bacaro Wine Bar, the first establishment in Santos Uy's L.A. empire, is turning four tomorrow evening on Union Avenue, and not-so-surprisingly, a drunken engagement is going down to mark the occasion. Make that a SEVEN HOUR drunken engagement, as Bacaro is offering an open bar and passed apps from five to midnight tomorrow evening. $20 buys entry for the fete, which will include DJs, along with the near endless indulgence in wine and tapas. In the four years since bringing Bacaro to South L.A., Uy has busied himself by opening Mignon in Downtown and last fall, a foray into Parisian-style bistronomy at the Los Feliz-based Papilles. Bacaro, 2308 S. Union Ave..