Lea's Tempura Batter Mix
1 box (40 oz) Bisquick
1 pkg (10 oz) potato starch (might be labeled "katakuriko")
1 box (1 lb) cornstarch
Combine all ingredients in a large bowl. Store in refrigerator. When ready to use, combine (only the amount needed) with cold water until desired consistency is reached. Fry between 350-375 degrees until golden brown.