Prepare the udon noodles according to package directions, then drain and set aside.
In a small bowl, whisk together the tamari, sesame oil, grated ginger, and minced garlic to create the stir-fry sauce.
Season the cubed chicken breast evenly with sea salt and black pepper.
Heat the avocado oil in a large skillet or wok over medium-high heat until shimmering.
Add the chicken to the skillet and cook until golden brown and cooked through, approximately 5-6 minutes.
Add the matchstick carrots and chopped baby bok choy to the skillet, sautéing for 2-3 minutes until the greens are wilted.
Incorporate the cooked udon noodles and the prepared sauce into the skillet.
Toss all ingredients together for 1-2 minutes until the noodles are well-coated and the dish is heated through.
Garnish with sesame seeds and serve immediately while hot.