Actually in Japan the sauce in takoyaki is brown. That's the authentic one. It's just that some special flavors use white sauce. In China if you want a creamy white one, there's probably only one kind. It's Chubby's salad dressing. There are many flavors in China, so you can see which one is the same as you said. Also, you can buy the brown one at places that sell Japanese food, like Carrefour and Tesco, although they have a very bad attitude. It comes in a big tube with the Japanese word "ソース" written on the bottle.