How to Make It
In a shallow bowl, lightly coat the sirloin with cornstarch and let stand for 15 minutes. Meanwhile, in a small bowl, whisk the beef stock with the vinegar, soy sauce, sherry, oyster sauce and sambal oelek.
In a wok or large, deep skillet, heat 1 inch of oil until shimmering. Add half of the sirloin and fry over high heat, stirring occasionally, until browned and crisp, about 4 minutes. Using a slotted spoon, transfer the sirloin to paper towels to drain. Repeat with the remaining sirloin.
Pour off all but 2 tablespoons of fat from the wok. Add the ginger, garlic, jalapeño and Thai chiles and stir-fry over high heat until fragrant, about 1 minute. Add the onion and asparagus and stir-fry until crisp-tender, about 4 minutes. Add the sirloin and the soy sauce mixture and simmer over high heat, stirring, until the sauce has thickened, about 2 minutes. Discard the dried chiles and season with salt. Transfer the Hunan beef to a platter and serve with rice.