3. Step
Add the remaining 1 tablespoon oil, asparagus and bell pepper to the pan; cook, stirring occasionally, until almost tender, about 4 minutes. Stir in scallion whites and garlic; cook, stirring, until fragrant, about 30 seconds. Whisk the sauce and add it to the pan along with the steak. Cook, stirring occasionally, until the sauce thickens, about 1 minute. Garnish with scallion greens.