Wash the black soybeans thoroughly and soak in water for at least 8 hours.
Boil the soaked black soybeans in boiling water for 20 minutes, then drain and let cool in a strainer.
Prepare nuts and seeds and cut them into bite-sized pieces.
Preheat the oven to 160°C (320°F).
In a bowl, mix the boiled black soybeans, oats, nuts, sunflower seeds, salt, olive oil, and maple syrup together.
Spread the mixture evenly on a baking sheet lined with parchment paper.
Bake in the preheated oven at 160°C (320°F) for 20 minutes, stirring once halfway through.
Take it out of the oven, let it cool, and store in an airtight container.