Heat the oil in a large pot set over medium heat. Add the shallots, bell peppers, garlic, and ginger. Cook, stirring, until tender, about 5 minutes.
Add the gochujang and miso paste and stir until well combined. Slowly pour in the broth, whisking constantly, until the mixture is smooth and homogenous. Stir in the coconut milk, toasted sesame oil, tamari, lime zest, and coconut sugar and bring to a rapid simmer. Once rapidly simmering, reduce the heat to a gentle simmer over medium-low heat.
Taste the broth and add salt, if desired. Note that a lot of the ingredients are pretty salty, so this is solely to taste. I add a pinch to mine, personally.
Add the sliced green onions and shrimp to the soup and stir to combine. Cover and cook until the shrimp is cooked through and no longer opaque, 4 to 6 minutes.
Finish with lime juice. Ladle the hot broth over prepared rice noodles and enjoy!