Heat 1 tbsp. oil in large nonstick skillet over medium-high heat; add pork and cook until golden; transfer to plate. Add remaining 2 tbsp. oil and sprouts to pan; cook, stirring occasionally, until brown and tender, 5 to 8 minutes. Add scallion whites and garlic; cook 1 minute. Add soy sauce, brown sugar and 1/4 cup water; cook until sauce is slightly thickened. Return pork to pan and toss to coat. Top with scallion greens.