Make a dough by mixing all ingredients for 15 minutes. Dough should be smooth and elastic. Cover and rest at room temperature until doubled in size. Divide dough into 2 equal doughs. Preheat oven to 200 C. (Fan-oven to 180 C.) Divide each dough again into equal parts and roll each into a long string, slightly bigger in the center. Lay two strings across and braid into zopf shape. Cover and let proof until doubled in size. Brush lightly with egg wash. Bake on lower tray for 45-50 minutes. Remove and cool on wire rack.