[1] He has taught opera and drama at the University of Victoria and Concordia University (Canada) and directed numerous theatre and opera productions on both sides of the Atlantic, including Carmen and Wozzeck in Canada, Cosi fan tutte (Czech Republic), Falstaff (Netherlands), Madama Butterfly (Austria)[2] and Krenek's Dark Waters at the Konzerthaus in Berlin.
He has also worked at Vancouver Opera, Teatro la Fenice in Venice, l'Opéra National du Rhin, the Deutsche Oper Berlin, and at important festivals in Italy, Austria, and the Netherlands, collaborating with directors such as Robert Carsen, Tim Albery, Brigitte Fassbaender, François Rochaix and Götz Friedrich and conductors Kenneth Montgomery, Yves Abel and Martin Fischer-Dieskau.
Together with pianist, Michael Abramovich, he directed Ensemble Alkan and produced the concert series 'Im buntesten Chaos – das Jüdische in der Musik' at Berlin's Jewish Museum.
[8] A history of Berlin's Staatsoper Unter den Linden 1918–1991, including a foreword by Daniel Barenboim, was published by Siedler Verlag/Random House, Germany in Fall 2017.
[9] A frequent contributor to The Walrus,[10] The Independent and Die Zeit (Germany), among others, Aster has presented lectures on music and media, history, and politics at the University of Cologne, Staatsoper Unter den Linden, the Gasteig (Munich), the Mariinsky Theater (St. Petersburg) and at London's Wiener Library.