1. Put steak in the freezer for 15 minutes while you 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 cooking, and set aside.
2. For sauce. Whisk 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 asparagus and fry, stirring constantly, for 2 minutes or until lightly browned. Remove 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 first batches of beef strips to pan along with bell pepper strips. Stir and toss over high heat until bell pepper strips are just beginning to wilt, 1-2 minutes. Quickly stir cornstarch liquid and add it to pan along with stir fry sauce. Cook until sauce thickens, 1-2 minutes. Return asparagus to the pan, toss to evenly coat.
Serve warm over steamed rice or noodles.