As the frontman of the legendary band Hothouse Flowers, the devastatingly charming singer-songwriter-raconteur-linguist Liam Ó Maonlaí has done as much as anyone to connect traditional Irish music with rock and roll. He took the 2014 FreshGrass festival by storm, singing half his solo set in Gaelic. He’s back, with some Hothouse bandmates in tow, for a very special St. Patrick’s Day show. Irish on tap.