For the sauce:
3 Tbsp reduced-sodium soy sauce
2 Tbsp cornstarch or arrowroot
1-1/2 cups water or vegetable stock
1 Tbsp minced ginger root
1 tsp sesame oil
1/4 tsp red pepper flakes, or more to taste
Dash of white pepper
2 Tbsp canola or safflower oil
1 lb fresh asparagus, woody parts of stems removed, tender part cut into 3-inch lengths (about 3 cups)
4 scallions, chopped
1 small sweet red pepper, chopped
1 clove garlic, minced
1 cup cashews, dry-roasted and unsalted
1 lb soba noodles, prepared according to package directions
In a small bowl, combine soy sauce and cornstarch. Stir in remaining sauce ingredients; set aside.
In a wok or large skillet, heat oil. Stir-fry asparagus, scallions, pepper, and garlic until vegetables are crisp-tender. Stir sauce mixture; pour it over the vegetables and stir until it is thickened and bubbly. Fold in cashews. Reduce heat, cover, and cook for 1 minute, until cashews are heated through.
Serve over soba noodles.