Put the bean sprouts in a pan with enough water to cover them, plus salt (1 teaspoon) and pepper (1/2 teaspoon). Boil over high heat.
Turn the heat off 2 to 3 minutes after the water comes to a boil, and strain the bean sprouts into a colander. If you stop cooking the soy bean sprouts too soon, they'll smell somewhat raw.
On the other hand if you cook them for too long you'll lose their crispy texture, so be careful here! (The smell of the boiling water will change once the beans have cooked properly.)
Once you drain the bean sprouts into a colander, add the grated garlic immediately and mix quickly. Crush the grated garlic with your fingers as you add it so that it doesn't clump.
The garlic will get cooked a little with the residual heat, so while the garlic aroma will remain, the taste won't be so harsh.
Spread the bean sprouts out so that there's a well in the middle of the colander. Leave until the sprouts have completely cooled.
Mix all the flavoring ingredients except for the sesame oil in a bowl with the bean sprouts. You can add a shake of pepper here too.
The sugar is a "secret" ingredient. You can leave it out if you like.
Start by adding 2 to 3 pinches of salt. Mix and taste, and add more a pinch at a time if you think it's needed. This way you can season properly and not mess up.
Add a little sesame oil and mix it in to finish.
Story Behind this Recipe
This has been a family recipe for a long time. It won't get watery even the next day, so the flavors don't get diluted and remains delicious.
Be sure to cool it down completely in Step 5! That way the sprouts won't get watery later and the flavors won't become diluted. In South Korea, they say that namul is easy to make but hard to season properly. When adding more salt or sugar, do so a pinch at a time! Be sure to taste as you go!