1. Put the steak in the freezer for 15 minutes while you prep your vegetables. This will make it easier to slice. Fill a medium-sized saucepan halfway with water and bring to a boil. Blanch the cut asparagus for 2 minutes. Drain, rinse with cold water to stop the cooking, and set aside.
2. For the sauce. Whisk all of the sauce ingredients together in a small bowl and set aside.
3. Heat 1 tablespoon of oil in a wok (or a thick-bottomed pot that can handle high heat) on high heat until shimmery. Add the asparagus and fry, stirring constantly, for 2 minutes or until lightly browned. Remove the asparagus from the pan and set aside.
4. In the same pan, stir fry the beef strips in batches, for 2 to 3 minutes per batch, until they are browned but still a little pink inside. Return the first batches of beef strips to the pan along with the bell pepper strips. Stir and toss over high heat until the bell pepper strips are just beginning to wilt, 1-2 minutes. Quickly stir the cornstarch liquid and add it to the pan along with the stir fry sauce. Cook until sauce thickens, 1-2 minutes. Return the asparagus to the pan, toss to evenly coat.
Serve warm over steamed rice or noodles.