1. Bring a large pot of water to a boil; remove pan from heat. Add noodles; let soak just until tender (about 8 minutes). Drain the noodles in a colander; rinse. Toss the noodles and 1 teaspoon sesame oil in a large bowl; set aside.
2. Add canola oil to pan; sautémushrooms over medium heat, stirring until soft and golden (about 2–3 minutes). Add broth, carrots, and ginger; simmer 5 minutes. Add shrimp; simmer until shrimp is cooked through (about 2 minutes). Stir in scallions, lime juice, soy sauce, and half of herbs.
3. Divide noodles among 4 serving bowls; ladle soup over noodles. Sprinkle soup with remaining herbs; drizzle each with the remaining sesame oil.