Stir-Fried Udon Noodles With Pork and Scallions

Name: Stir-Fried Udon Noodles With Pork and Scallions
Cuisine: Japanese
Ingredients: 2 tablespoons vegetable oil, divided; 4 cups very coarsely chopped green cabbage (from about ¼ medium head); 2 7-ounce packages instant udon noodles, flavor packets discarded; 2 teaspoons toasted sesame oil; 8 ounces ground pork; 5 scallions, white and pale-green parts coarsely chopped, dark-green parts thinly sliced; 2 teaspoons finely grated fresh ginger (from a 1-inch knob); 1 teaspoon crushed red pepper flakes; ⅓ cup mirin; ⅓ cup soy sauce; 1 tablespoon toasted sesame seeds, plus more for serving