Mise en place - Finely mince the ginger. You don't need to peel it, but you should trim away any dry bits. Peel and mince the garlic. Trim and thinly slice the scallions, white and green parts, and set aside.
Sauté the aromatics -Heat 1 tablespoon of sesame oil over medium heat. Add the minced ginger, minced garlic, and white parts of the scallions, then sauté briefly, only until fragrant.
Simmer - Pour in the chicken broth and tamari, and bring the mixture to a boil, then reduce the heat to a simmer. Stir in the rice vinegar, and miso paste.
Finish and Serve - Turn off the heat. Stir in a handful of fresh spinach until just wilted, then add a tablespoon of toasted sesame oil and the green parts of the scallions.