Make marinade by combining tamari, ginger, garlic, sesame oil, maple syrup, apple cider vinegar and red pepper flakes in a shallow container. Cut tempeh into thin slices and add to the container with the marinade. Toss to coat tempeh and set aside. Let the tempeh marinate anywhere from 30 minutes to overnight.
Once tempeh has marinated, you’re ready to start the broth. Add 1 teaspoon of coconut oil to a large pot over medium heat. Add garlic and sauté until fragrant. Add shiitake mushrooms and chopped bok choy and sauté a bit longer — about 5 minutes. Add carrots, ginger, miso, Chinese five spice, vegetable stock and water into the pot and bring mixture to a boil. Once boiling, reduce heat and let simmer for 15-20 minutes.
While broth is simmering, add 1 teaspoon coconut oil to a large skillet over medium heat. Once oil is hot, add marinated tempeh to the skillet and pour any remaining marinade into the pot with the broth for extra seasoning. Cook tempeh for 3 minutes on each side or until all the pieces are a little brown. Remove from heat and set aside.
Divide zucchini noodles evenly among 4 bowls.
Once broth has simmered, taste and add tamari if needed. Ladle a little over 1 cup of warm mushroom broth into each bowl. Arrange extra bok choy leaves and a nori sheet around edges of the bowls. Place a few slices of tempeh in each bowl; top evenly with green onions and sesame seeds and serve immediately. Top with Sriracha or chili garlic sauce, if using.