Thai Coconut Soup with Bean-Thread Noodles

In large saucepot, heat 3 quarts water to boiling over high heat; remove saucepot from heat. Place noodles in water; soak 10 to 15 minutes, just until transparent (do not oversoak). Meanwhile, in 5-quart Dutch oven, heat 1/2 cup coconut milk to boiling over medium heat. Add garlic, ginger, coriander, cumin, and ground red pepper, and cook 1 minute, stirring. Increase heat to medium-high; add chicken and cook just until it loses its pink color throughout, stirring constantly. (If using tofu, add with remaining coconut milk in step 3.) Drain noodles; rinse with cold running water and drain again. With kitchen shears, cut noodles into shorter lengths. To mixture in Dutch oven, add broth, green onions, carrots, red peppers, fish sauce, noodles, 1 cup water, remaining coconut milk, and tofu if using; heat just to simmering over medium-high heat, stirring occasionally. Stir in lime juice and cilantro just before serving.