1. Cook noodles according to package directions; drain.
2. Heat a large wok or skillet over high heat. Add 1 tablespoon oil to pan; swirl to coat. Add shrimp; stir-fry 4 minutes. Remove shrimp from pan. Return pan to high heat. Add remaining 1 tablespoon oil; swirl to coat. Add onion, celery, lemongrass, and ginger; stir-fry 1 minute. Combine coconut milk and next 4 ingredients (through fish sauce) in a bowl, stirring with a whisk until sugar dissolves. Add coconut milk mixture to pan; cook 3 minutes or until sauce is slightly thickened.
3. Add noodles, shrimp, bean sprouts, basil, and mint to pan; toss to coat. Divide noodle mixture among 4 shallow bowls; sprinkle with cashews and celery leaves. Serve with lime wedges.