January was a busy month for Felix Bollen. The co-owner of German Kraft Brewery spent new year’s eve in Austria before heading to Berlin, where he lives, a week later. Two weeks on, he took a bus to London, the birthplace of German Kraft (his car —“a piece of shit,” he says, with a smile—broke down en route) before flying back to the German capital for a few days. He ended the month back in Vienna. Such is Felix’s life now. German Kraft, which he founded alongside pals Michele Tie...