Step 1

In a medium bowl, stir together the soy sauce, water, mirin, sugar, cornstarch, black pepper, red pepper flakes and mustard. Set aside.

Step 2

Bring a large pot of water to a boil. Cook the pasta according to the package instructions. Drain and set aside.

Step 3

Return the pot to your stove and warm the vegetable oil over medium-high heat. Add about half of the green beans and cook, stirring occasionally, until their skin starts to blister in a few places, about 3-4 minutes. Transfer to a clean plate and then cook the remaining green beans in the same manner, adding more vegetable oil to the pot if it starts to get dry on the bottom. Remove the green beans and add them to the plate with the others.

Step 4

Return the pot to your stove and warm the sesame oil over medium heat. Add the mushrooms and cook, stirring frequently, for about 2 minutes. Add the garlic and ginger and cook, stirring frequently, for about 1 minute.

Step 5

Give the sauce a quick stir to recombine it. Then add it to the pot along with the cooked pasta and green beans. Toss to combine all the ingredients and coat them in the sauce. Remove the pot from the heat. Add the scallions and mint and toss to combine.

Step 6

This dish can be enjoyed warm or at room temperature. Leftovers can be stored in an airtight container in your refrigerator for 2-3 days.