Bring a small pot of water to a boil, carefully lower the egg into the water, and simmer for 6 minutes and 30 seconds before transferring to an ice bath.
Cook the soba noodles in boiling water according to package directions, then drain and set aside.
In a small bowl, whisk together the gochujang, tamari, rice vinegar, and a splash of water to create a smooth sauce.
Heat the toasted sesame oil in a skillet over medium-high heat and sauté the diced chicken breast until golden and cooked through.
Add the minced garlic and grated ginger to the skillet, cooking for 1 minute until fragrant.
Toss the baby bok choy into the skillet with a tablespoon of water, covering for 2 minutes to steam until tender-crisp.
Add the cooked noodles and the gochujang sauce to the skillet, tossing everything together until the noodles are well-coated and the sauce is thickened.
Peel the soft-boiled egg and slice it in half.
Serve the ramen in a bowl topped with the egg halves and thinly sliced green onions.