Prep the noodles. Cook noodles according to package directions until just tender. Drain, rinse briefly with cool water, and set aside.
Toss with a little oil to prevent sticking.
Warm the aromatics. In a large pot, heat 1–2 tablespoons oil over medium heat. Add shallot/onion, garlic, and ginger. Cook 2–3 minutes until fragrant and softened, but not browned.
Bloom the curry paste. Stir in the red curry paste and cook 1 minute, pressing it into the pot.
This step unlocks deeper flavor.
Build the broth. Pour in the coconut milk and 3 cups broth. Add fish sauce (or soy) and sugar. Stir and bring to a gentle simmer.
Add protein and veggies. If using chicken, add it now and simmer 5–7 minutes until cooked through.
For shrimp, add in the last 3 minutes. For tofu or mushrooms, add with vegetables. Then add bell pepper, carrots, and snap peas; simmer 3–5 minutes until crisp-tender.
Adjust the flavor. Add lime zest and juice.
Taste and adjust with more fish/soy sauce for salt, sugar for balance, or extra curry paste for heat. If the broth is too strong, add more broth to thin.
Combine with noodles. Divide noodles into bowls and ladle hot soup over them, or stir noodles directly into the pot right before serving.
Finish with toppings. Sprinkle with cilantro, Thai basil, scallions, and sliced chili. Add bean sprouts and extra lime wedges.
Drizzle chili oil if you like heat.