Rinse 300g of black soybeans and soak them in water for at least 6 hours. During hot seasons, soak them in the refrigerator.

Drain the soaked soybeans and place them in a pot. Add 3-4 pieces of kombu and 1/2 tbsp salt. Pour in 1500ml of water.

Boil uncovered on high heat until it starts to boil, then reduce to medium heat and simmer for 15 minutes. Skim off any foam that forms.

Cool the cooked soybeans and blend them in a mixer with the broth. Optionally, add sesame seeds, perilla seeds, or nuts for extra flavor. Adjust water to your preferred consistency and blend until smooth.