Heat oil in a large saucepan over medium heat. Add garlic, ginger and crushed red pepper; cook, stirring, until fragrant, about 1 minute. Add miso. Slowly whisk in broth, stirring, until the miso is dissolved. Increase heat to high and bring to a boil. Add noodles; reduce heat to maintain a lively simmer and cook, stirring occasionally, until the noodles are cooked through, about 8 minutes.
