How to Make It
Bring broth, soy sauce, vinegar, ginger, bell pepper, and Serrano to a boil in a large saucepan over high. Reduce heat to medium-low, and simmer until fragrant, about 10 minutes.
Meanwhile, preheat broiler to high with oven rack 5 inches from heat. Place scallions in a single layer on an foil-lined baking sheet; broil until charred, 3 to 5 minutes. Let cool.
Gently lower eggs into simmering broth mixture, and cook 10 minutes. Reserving broth, use a slotted spoon to transfer eggs to a bowl of ice water. Remove broth from heat and cover to keep warm. Let eggs cool 5 minutes, then peel and cut in half.
Meanwhile, return broth mixture to a simmer; add scallions and noodles. Cook, stirring occasionally, until noodles are tender, about 4 minutes. Divide soup among 4 bowls. Top with eggs, cilantro and Fresno chili.