Bean sprouts are mung beans.

http://www.lowcarb.ca/low-carb-tool...l?item_id=11044
http://www.lowcarb.ca/low-carb-tool...l?item_id=11045

I don't know why there's a massive difference between boiled and stirfried, especially when it's going by weight and not volume

Maybe they absorb water when boiled which makes them heavier and therefore less carbs, and when stir-fryed they give out water, making them lighter and concentrating the carbs.... maybe someone will know for sure!