Thaw shrimp, if frozen. Peel and devein shrimp. Rinse shrimp; pat dry with paper towels. Set aside. Diagonally slice the whole green onions into 1-inch-long pieces, keeping white parts separate from green tops. Set green tops aside. In a large nonstick saucepan heat oil over medium heat. Add white parts of the green onions, the carrots, and mushrooms; cook for 5 minutes, stirring occasionally. Add ginger and garlic; cook and stir for 1 minute more.
Add chicken broth, the water, soybeans, soy sauce, and, if desired, crushed red pepper to mushroom mixture. Bring to boiling; reduce heat. Cover and simmer about 5 minutes or just until carrots are tender.
Add shrimp and pea pods and/or bok choy. Return to boiling; reduce heat. Simmer, uncovered, for 2 to 3 minutes or until shrimp are opaque. Stir in green onion tops just before serving. If desired, garnish with slivered green onions.