@Tes yeux noirs,
They (Michael Heyne and Dominik Stein) are from Beilheim (in southern Germany).
After having finished university, they learnt how to make Döner at their local Döner restaurant, got some additional studies in Berlin and Hamburg (mainly by eating up to 40 Döners a day), learnt, how to bake döner bread in Stuttgart .... and opened their first restaurant in Austin in 2011 (they had studied there as well). All the material for the restaurant have been imported from Germany besides the refrigerators, they are from Austria.
The invested money comes completely from their families and friends in Germany.