1. In a small cooking pot, add all the soba tsuyu ingredients and bring it to a boil. Reduce the heat to low and simmer for about 1 min. Remove from the heat and set aside until it cools down. Then keep the sauce in an airtight container and store in the refrigerator until soba is ready.
2. In a large cooking pot, boil a potfull of water. Cook the soba noodles according to the package instructions (they depend on which kind of soba or brand you use). Or until your favorite tenderness.
3. Rinse the soba noodles in the cold water to get rid of starch before you serve.
4. Drain completely and divide soba among the serving plates. Garnish with shredded nori sheet on top.
5. Pour enough "soba tsuyu" from the fridge into a small bowl for dipping the soba and serve with a side of sliced leek and wasabi.