Season the chicken cutlets with salt and pepper on both sides.
Heat oil in a Dutch oven or pot. Cook chicken on both sides for 3-4 minutes per side or until it reaches 165°F (74°C). Remove and set aside.
In the same pot, add sesame oil and shiitake mushrooms. Cook for 3-4 minutes. Remove and set aside.
If needed, add a teaspoon of vegetable or avocado oil to the pot. Add garlic and ginger; cook for 1 minute.
Add chicken/vegetable stock and soy sauce; bring to a boil, then reduce the heat and simmer for 2-3 minutes. Remove from heat. Taste the broth and adjust seasoning (add more soy sauce) if needed.
While the broth simmers, boil water in a separate pot. Add noodles and cook according to package instructions (if using straight noodles, it’s usually 5 minutes, instant ramen noodles usually cook in 3 minutes). Add bok choi to the same water; blanch for 2-3 minutes. Remove and set aside.
To assemble, put noodles in a bowl, add bok choi, and pour the broth on top. Slice the chicken and add it to the bowl. Add cooked mushrooms, a sliced soft-boiled egg, sliced green onions, a sprinkle of sesame seeds (I used black and white), and a drizzle of sriracha if you like.