Line a rimmed baking sheet with parchment paper, then preheat a broiler to high. In a large bowl, combine ground pork, large egg, breadcrumbs, chopped mint, grated garlic, ginger paste, low-sodium soy sauce, sesame oil, and fish sauce.
Lightly wet your hands with water, then take about 2 tablespoons of the mixture at a time and roll into uniform spheres. Place on the prepared baking sheet. Repeat until all meatballs are formed.
Place under a broiler, then cook on the first side. Remove from the oven, carefully flip the meatballs over, and cook an additional 4-5 minutes on the second side.
In a large pot, heat neutral oil over medium-high heat. Add half of the thinly sliced scallions and maitake mushrooms, stir, then cook undisturbed. Once the mushrooms have browned a bit, season.
Add low-sodium chicken broth, then stir in the sliced ginger and dark soy sauce. Bring the mixture to a boil, then reduce to a simmer. Cook.
Stir in rice wine vinegar, then taste and adjust seasoning as needed. Carefully add the meatballs to the broth and simmer.
Meatballs can be enjoyed in bowls as is or spooned on top of rice or noodles. Before serving, sprinkle with a spoonful of chili oil, the remaining thinly sliced green onions, and fresh cilantro. Enjoy immediately with lime wedges on the side.