How self-identified political liberals voted in the 2012 presidential election, by race:
Sample sizes are 327, 84, and 50, respectively.
Surprised that not a single black liberal voted for Romney? Don't be, there's plenty of precedence. Exit polling from New York state had a black sample larger than this in 2008 and they didn't find a single black--liberal, moderate, conservative, or otherwise--who voted for McCain.
GSS variables used: RACECEN1(1)(2), HISPANIC(2-98), POLVIEWS(1-3), PRES12(1-2)