Step 1

Stir together the stock, scallions, garlic, ginger, lemongrass, carrots, and mushrooms in a 5- to 6-quart slow cooker. Cover and cook on LOW until the vegetables are tender and the broth is aromatic, 3 to 4 hours. Remove and discard the lemongrass. Stir in the lime juice, fish sauce, and shrimp; cover and cook on LOW until the shrimp turn pink, about 10 minutes.

Step 2

Meanwhile, soak the rice vermicelli according to the package directions; divide among 6 bowls. Ladle the broth over the noodles. Top with the shrimp mixture. Top evenly with the bean sprouts, chile slices, basil, and cilantro.