Hao Cai Lei was my go-to Asian supermarket when I was living in Berlin. It's only a few minutes…read moreaway from the Hermannplatz station. They even provide you plastic bags for free. The woman behind the counter speaks Chinese and is very friendly and helpful.
Hao Cai Lei carries a wide selection of Asian foods, drinks, spices, even homeware. They have a small fresh section (with vegetables like bok choy, Thai chilis, chives, enoki mushrooms) and an extensive frozen section (dumpling wrappers, frozen dumplings, Korean rice cakes, frozen shrimp, frozen calamari). They also have a wide array of sauces (soy sauces in different darknesses, hoisin sauce, etc) and noodles (udon, ramen, somen, soba, pho, all sorts of rice noodles). I also bought seaweed and sesame seeds here; I found sesame seeds rather hard to find in other German grocery stores. Hao Cai Lei also carries Ramune! They even sell chopsticks, bowls, dim sum containers, etc.
Bottom line: fantastic selection of Asian foods in a convenient location, anything you have had trouble finding, you can probably find here.