Wash the surface of the burdock root with a brush and then cut it into long, thin slivers or thin diagonal slices. (Don't peel it. You don't need to rinse it, either)
Cut the beef into thin 1 cm strips.
Add vegetable oil to a pot and stir-fry the burdock root.
When the burdock root has wilted, throw in the beef. Stir-fry, breaking up the meat to separate it.
When the meat is cooked through, add the 2 tablespoons of sake, followed by the 4 tablespoons of sugar. Stir to dissolve the sugar.
Add the 4 tablespoons of soy sauce and stir-fry again. Finally, add the mirin and stir. Simmer until the liquid is boiled down and turn off the heat.
Boil the soba noodles (or udon noodles) and put them in bowls. Pour in some mentsuyu and add the toppings.
The beef is also good on top of rice.
Story Behind this Recipe
When my husband's family in Kumamoto makes 'Toshikoshi soba' (New Year's Eve soba noodles), they make this "Meat Soba". It tastes just like mom's cooking.
The burdock root tastes more delicious if you don't peel it or soak it (try it and you'll understand!). When you add the seasonings, add the sugar first, before the soy sauce (the molecules in the sugar are bigger than the ones in the soy sauce, so the meat takes longer to absorb the sugar). The flavor is pretty strong.