1. Combine first 6 ingredients in a small bowl, stirring well with a whisk.
2. Heat a large skillet over high heat. Add 1 tablespoon oil to pan; swirl to coat. Add beef; stir-fry until browned but not cooked through (about 1 1/2 minutes). Place beef on a plate; discard liquid in pan.
3. Return pan to high heat. Add remaining 2 teaspoons oil; swirl to coat. Add asparagus and bell pepper; stir-fry 2 minutes. Add crushed red pepper and green onions; stir-fry 30 seconds. Reduce heat to medium-high. Add stock mixture; cook 3 minutes or until sauce is slightly thickened. Return beef and any juices to pan, and cook for 1 minute.
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