Mung bean sprouts are widely used in Chinese food. They are very delicate and tend to wilt rapidly in heat. Cooking them will make them wilt and lose the crunch. In Chinese cuisine, they are normally stir fried.
My mother used to make a salad with bean sprouts, and I really enjoyed the dish. I am sure that she must have picked up the recipe from her Nyonya friends. In my home, it was never presented as a salad. Instead, it was a subzi (main dish) to accompany rice and a dal or other wet preparations that were mixed with the rice. Whichever way you decide to consume it, it is delicious.
The traditional recipe uses only bean sprouts and some garlic. My mother substituted garlic with onions (we did not consume garlic). Sometimes, fried tofu was also added. I was keen to add thin slivers of capsicum (green bell pepper) and carrots. However, Hari decided to go traditional and did not add anything else.

Ingredients
1 garlic clove, chopped
2 tbsp light soya sauce
100 gms firm tofu, cut into medium sized cubes (optional)
100 gms green bell peppers, slivered (optional)
100 gms carrots, slivered (optional)
400 gms bean sprouts (taugeh in Mandarin, I think)
3 tbsp water
1/4 tsp white pepper powder (use black if you do not have white handy)
Additional 400 ml water
Salt (only if the bell peppers and carrots are being sauteed)
Method
Air fry the tofu cubes till the are a little crunchy (if using, otherwise skip this step)
Set aside
Heat a wok and add bell pepper and carrot (if using, otherwise skip this step)
Add a pinch of salt and very little water (only if strictly necessary)
Cook the vegetables, but ensure that they are still crunchy (perhaps about a minute)
Set aside
Heat the same wok and add the garlic
Sauté till golden brown
Set aside
Add soya sauce, white pepper and 3 tbsp water to a pan
Heat on low flame till warm
Remove from heat and set aside
Pour 400 ml water into a pan and bring to boil
Switch off flame and add bean sprouts
After 60 seconds, transfer to cold water (blanching)
Wait for a minute and drain the water
Transfer to a serving bowl
Add the garlic and vegetables
Pour the soya sauce mixture over the sprouts
Mix well
Serve immediately
Enjoy!
Note: You can also add the bell pepper and carrot raw