Peel ginger, and cut into thin strips. Cut green onions into 2-inch thin strips; set ginger and green onions aside.
Pour 1/4 cup vegetable oil into a large skillet; place over high heat until hot. Add garlic, and cook, stirring constantly, 5 to 7 seconds; remove and discard garlic. Add spinach to skillet; cook, stirring constantly, until lightly wilted. Spoon spinach onto serving plates, and keep warm.
Place fish in a steamer basket or bamboo steamer over boiling water; cover and steam 8 minutes or until fish flakes easily when tested with a fork. Place fish on spinach; top with ginger and green onions.
Combine remaining 1/4 cup vegetable oil and sesame oil in skillet; place over high heat until hot. Drizzle over fish.
Bring soy sauce and next 3 ingredients to a boil in skillet. Drizzle half of mixture over fish; serve immediately with remaining mixture.