Prepare the enoki mushrooms by cutting off the bottom root section. Gently rinse with cold water to remove any excess dirt, then section the mushrooms into 15 smaller bunches to be wrapped.
Wrap each bunch with a thin slice of beef to hold them together 3. Set aside.
Combine all the ingredients for the sauce until smooth, and set aside for later cooking.
In a pan, heat 2 tsp of oil over medium heat. Sauté the onions until softened, about 4-5 minutes.
Lay the enoki beef rolls over the onions. Pour the prepared sauce over the rolls and simmer with a lid for about 5 minutes until the mushrooms have softened.
Pour the scrambled egg on top of the rolls, place the lid on again, and cook for an additional 1 minute, or until the eggs are slightly set 4.
Let cool. Top with the chopped scallions. Enjoy with a side of rice and/or vegetables.
Sake can be replaced with any standard cooking wine, such as dry white wine or even Chinese Shaoxing wine. Alternatively, you may choose to omit the sake without sacrificing the taste of the dish too much.
Similar to sake, this can also be omitted without drastically altering the taste of the recipe. However, if omitting, I’d suggest adding ½ tsp of sugar instead to account for the loss of sweetness.
A quick tip I found to keep the rolls from unravelling and breaking apart is by wrapping your mushrooms with partially frozen beef -that is, when the slices aren’t completely at room temperature yet, but still soft and pliable enough to roll. This keeps the rolls stable without the meat falling apart!
The longer you cook the sauce, the more concentrated and drier the overall dish is (this is actually very tasty, as the sauce begins to caramelize and browns the beef!). You can also keep the sauce soupy (great to pour over rice) by adding a touch more dashi or removing it from the heat early.