Start by making the soup. To do so, you will need to soak the kombu pieces in the cold water for the soup in a large pot overnight.

When ready to cook, bring the water to a boil. Scoop out the pieces of kombu just before the water begins to boil.

Once the water is boiling, sprinkle in the bonito flakes. Turn off the heat and allow flakes to steep in the liquid for 10 minutes.

Strain the stock through a fine mesh sieve, returning the strained liquid to the pot. Bring to a boil again over medium-high heat, and stir in sake, mirin, soy sauce and salt. Season to taste with additional soy sauce and mirin. Once boiling, add the fresh udon noodles.

Cover and cook for 30 seconds to 1 minute until they are cooked through. Keep warm over low heat until ready to serve.

Using a mandoline set to 1/4-inch thickness, slice the sweet potato, turnip, potato and carrots. Set aside.

Fill a pot approximately 2 inches deep with canola oil. Heat over medium heat to 360 degrees F. Be sure to keep the oil at this temperature throughout the frying process, adjusting your heat up or down as required.

While the oil heats up, add egg, flour, cold water and salt for the tempura batter to a medium bowl. Whisk for one to two minutes, until smooth. Place this bowl in a second, larger bowl filled with ice to keep the batter cool.

When the oil it hot, use stainless steel chopsticks to dip the various vegetables into the batter and then carefully place them into the hot oil. Working in batches of approximately 5-7 pieces per pot, without overcrowding, fry the vegetables for about 3 minutes until the pieces are a light golden brown.

Remove the pieces to a sheet pan lined with paper towels. Serve tempura vegetables immediately with the udon noodle soup.