Heat coconut oil in a large pot over medium heat. Add the onion, carrot, and bell pepper, and cook for a few minutes until the onion is translucent. Stir in the garlic, ginger, and red curry paste, and cook for a few minutes until fragrant, being careful not to burn the spices.
Pour in the vegetable broth and coconut milk. Add the peanut butter, using your spoon to break it up in the pot, followed by the lime juice and soy sauce. Increase heat to bring to a boil, then reduce to a simmer and cook for 10 minutes.
Increase heat to medium-high to produce a gentle boil, then add the vermicelli to the pot. Cook for 3 to 5 minutes until tender, or follow the instructions on the package.
Remove the soup from heat, and stir in the fresh cilantro and mint. Ladle the soup into bowls, and top with chopped peanuts before serving.
Other possible toppings: more lime juice, chopped scallions, hot sauce, red chili or jalapeno peppers, bean sprouts
If you do not want this to be vegetarian, shredded chicken is a nice addition that also adds more protein.
I highly recommend using authentic rice vermicelli, which can be found online or in the international aisle of most large grocery stores (including Whole Foods). You can substitute other types of thin rice noodles, but I found that they absorb more liquid than the vermicelli and the soup is less brothy with them.
Store leftovers in an airtight container in the fridge for up to three days. Reheat in a saucepan over medium-low heat, stirring frequently, until warmed through.