Cook the soba noodles in boiling water according to package directions, then drain and set aside.
Slice the chicken breast into thin, bite-sized strips.
Heat the avocado oil in a large skillet or wok over medium-high heat until shimmering.
Add the chicken strips to the skillet and cook until golden brown and cooked through, about 5-6 minutes.
Toss in the broccoli florets, sliced red bell pepper, and sugar snap peas, stir-frying until they are tender-crisp.
Add the minced garlic, grated ginger, and red pepper flakes to the pan, stirring constantly for 1 minute until highly fragrant.
Add the cooked soba noodles, tamari, and toasted sesame oil to the skillet, tossing everything together until well-combined and heated through.
Divide the stir-fry into bowls and garnish with sesame seeds before serving hot.