Cook the noodles according to the package instructions. Drain and rinse under cold water and set aside.
In a large pot, add the oil, white and light green scallions, and ¼ teaspoon salt. Cook for 3 minutes, stirring occasionally, or until softened. Add the garlic and red pepper flakes and cook for about 30 seconds, stirring constantly.
Stir in the water, veggies, kombu (if using), ginger, soy sauce, and remaining ½ teaspoon salt. Cover and bring to a boil over high heat. Give it a stir, then reduce the heat to low/medium-low and simmer, covered, for 15 minutes. Remove from heat. Remove the kombu (if using).
Transfer 1 cup of broth to a blender along with the almond butter and miso paste and blend on high until smooth (make sure to allow steam to escape!). You could also do this with a fork and/or whisk in a bowl, but I find the blender creates a much smoother consistency. Stir it back into the pot along with the greens (if using) and lemon.
Ladle soup to a bowl and add your rice noodles. Top with the green parts of the scallions and a boiled egg (if using).