The next day, prep the vegetables. First, halve or quarter the turnip, depending on size, and spiralize using the attachment for spaghetti-sized noodles. Prep the other vegetables and optional add-ins. Julienne reserved green onion tops.
Pour broth into a medium stockpot that can accommodate a steamer basket. Carefully tip marinating liquid into the broth. Bring to a boil, then turn down to a lively simmer for 10 minutes. Taste broth – it will be quite richly flavored, add a cup of water if desired. Set chicken in steamer basket, and set above simmering broth. Cover and cook 8 - 12 minutes, or until the internal temperature hits 165 degrees F. Rest until chicken is cool enough to handle, then cut on the bias into 1/2-inch thick slices.
Meanwhile, heat a 12-inch skillet over medium/medium-high heat; the skillet should be hot, but not smoking – adjust heat down as needed. Add 1 tablespoon oil, and when hot and shimmering, add half the turnip noodles and a pinch of sea salt, and sauté 5 minutes or until noodles are just tender. Repeat for second batch. Scrape out noodles, and with heat still on medium/medium-high, add 1 tablespoon oil, 2 minced cloves garlic, mushrooms, and a pinch sea salt. Sauté until mushrooms are charred on the edges and have released their water. Scrape out of pan. Add remaining tablespoon oil to the hot pan and sear bok choy, about 2 minutes a side. Sprinkle with sea salt.
*For Whole30 compliance, before marinating, sprinkle chicken with 1 teaspoon sea salt and sub 1 cup coconut aminos in place of soy sauce and mirin mixture.