Who has the Most strikeouts for a left handed pitcher?

Tom Cheney, pitching for the Washington Senators. He struck out 21 Baltimore Orioles in a 16 inning complete game victory September 12th 1962.

Since then, Roger Clemens and Kerry Wood are currently tied. Clemens struck out 20 in a game in both 1986 and 1996. Wood struck out 20 in a game in 1998. Randy Johnson struck out 20 over nine innings in a game during the 2001 season, but is not recognized as a record-holder because he was removed from the game which took 11 innings to complete.