START TO FINISH: 40 minutes
SERVINGS: 4
Chewy Japanese udon noodles make this a light but satisfying meal. We used white miso and soy sauce to quickly marinate the pork before cooking and to add deep, savory flavors to the simple chicken broth base. Check instructions on the udon package for cooking times, but make sure to test a noodle for doneness at least a minute or two before they’re supposed to be done.
Don’t rinse the drained noodles under cold water. Use lukewarm water to prevent them from cooling completely and keep the soup hot.
4 tablespoons white miso, divided
2 tablespoons soy sauce, divided
1-pound pork tenderloin, trimmed of silver skin
4 ounces dried udon noodles
1½ quarts low-sodium chicken broth
1 tablespoon finely grated fresh ginger
1 jalapeño chili, stemmed and sliced into thin rings
8 scallions, sliced thinly on diagonal, whites and greens reserved separately
8 ounces (10 cups) baby spinach
3 tablespoons unseasoned rice vinegar
In a large pot, bring 4 quarts of water to a boil. Meanwhile, in a medium bowl, mix 1 tablespoon each of the miso and soy sauce. Cut the tenderloin in half lengthwise, then slice each half crosswise about ¼ inch thick. Add the pork to the bowl and stir. Set aside at room temperature.
While the pork marinates, add the noodles to the boiling water and cook until tender. Drain, rinse under lukewarm water, drain again, then divide among 4 serving bowls. Set aside.
In the pot used to cook the noodles, bring the broth to a boil over medium-high. In a small bowl, whisk the remaining 3 tablespoons miso with 2 tablespoons of the broth. Add the mixture to the pot along with the remaining 1 tablespoon soy sauce, the ginger, half of the jalapeños and the scallion whites. Reduce to medium and simmer gently for 10 minutes.
Return the broth to a boil over medium-high. Add the pork and cook, stirring occasionally, until cooked through, about 2 minutes. Off heat, stir in the spinach and vinegar. Ladle the soup over the noodles, then sprinkle with the scallion greens and the remaining jalapeños.