Preheat your oven to 350°F. Spread the cashews in a pie plate and toast them in the oven for about 8 minutes, until they are nicely browned and fragrant. Let cool.
In a medium bowl, toss the chicken with 1 tablespoon of the fish sauce. In a wok or large skillet, heat the vegetable oil until shimmering. Add the chicken in an even layer and cook over high heat, turning once, until browned and just cooked throughout, about 4 minutes. Using a slotted spoon, transfer the chicken to a clean bowl.
Pour the chicken broth into the wok and bring to a simmer, scraping up any browned bits. Add the asparagus slices, cover and cook over moderate heat until they are crisp-tender, about 3 minutes. Using a slotted spoon, transfer the asparagus to the bowl along with the chicken.
Add the remaining 1 tablespoon of fish sauce to the wok along with the oyster sauce, lime juice and cayenne pepper. Simmer until the sauce is reduced to ⅓ cup, about 2 minutes. Return the chicken pieces and sliced asparagus to the wok and toss to heat through. Remove the wok from the heat and stir in the cashews, basil and chives. Season the stir fry with black pepper and serve immediately.
