The reason why mung bean sprouts are bitter when fried: 1. Green bean sprouts should be covered tightly from light, and the bean sprouts that leak light will change color and become bitter. 2, mung bean sprouts are old, have faded for a long time, and will be bitter when fried. 3. Too much salt will make you bitter. Boil the water and you can fry it. When it's almost done, add some salt, add some vinegar and stir-fry for a few times.