**Sauté Aromatics:** Heat vegetable oil in a large pot over medium heat. Add the onion and cook until softened, about 3 minutes. Stir in the garlic and ginger, cooking for another minute until fragrant.
**Cook Curry Paste:** Add the red curry paste and chili flakes to the pot, stirring constantly for about 1–2 minutes to release the flavors.
**Make the Broth:** Pour in the coconut milk, chicken or vegetable broth, soy sauce, fish sauce (if using), and brown sugar. Stir well and bring to a gentle simmer.
**Add Noodles and Protein:** Add the ramen noodles to the pot, breaking them apart as they cook. Stir in your choice of cooked chicken, shrimp, or tofu, along with the vegetables. Simmer for 5–7 minutes until the noodles are tender and the vegetables are cooked to your liking.
**Finish with Lime:** Remove the pot from heat and stir in the lime juice.
**Serve:** Ladle the ramen into bowls and garnish with fresh cilantro, green onions, and additional chili flakes if desired.