Slice the onion thinly. Cut the root ends off the shimeji mushrooms and shred. Chop up the shiso leaves.
Stir fry the ingredients from step 1 (except for the shiso leaves) in 20 g of butter.
When it's all wilted, add the cake flour, and mix until it's no longer floury.
Turn off the heat and add the milk and tarako. It's easy to break up the tarako on top of a wooden spatula, using a fork. (If you don't like the membrane, this wouldn't work for you, just scrape out the insides and add that to the pan.)
Turn the heat back on, add the remaining 10 g of butter, and simmer while mixing until the sauce is creamy.
Boil the pasta in generously salted water.
Just before the pasta is done, add about 2 ladles full of the cooking water to the pan with the sauce. Add the soy sauce, and adjust the seasoning with salt and pepper.
When the pasta is done, drain, put back in the pan, and mix with the sauce from Step 7.
Transfer to serving plates, scatter chopped shiso leaves and enjoy.
Story Behind this Recipe
I love pasta, so I made this because I wanted to increase my repertoire.
If you use fresh cream instead of milk, you probably don't need flour.