Supposedly he got the DKiG based on his performance during the Stalingrad campaign. I./KG100 was fighting there / transporting goods into the pocket.
On the date of awarding, the Gruppe was already on the Crimea (Saki) for rest and later went to South France for training with the new Lotfe 7D before returning to the Ukraine in time for the summer campaign 1943.
Also see
http://ww2.dk/air/kampf/kg100.htm
PS: Yes, the Balke-book is a expensive, but also quite good. At a short glance, I couldn't find the G. Strelow in the book.