Combine the sauce ingredients in a food processor or blender. Blend until smooth - adding water as needed. Taste and adjust seasonings as needed.* Set aside.
Bring a large pot of water to a boil. Add the pasta and cook according to the package instructions.
When the pasta is 2 minutes from being done, add the bok choy to the pot. Boil for the remaining 2 minutes and remove the bok choy with tongs. Drain the pasta.
Place the empty pot back on the stove with no heat. Add the noodles, sauce and cilantro. Toss until combined.
Serve immediately with the bok choy, green onions, sesame seeds, red pepper flakes and lime wedges.
*Tahini is naturally bitter - if the sauce tastes too bitter you can add a little more soy sauce.
Calories: 485kcal, Carbohydrates: 56g, Protein: 14g, Fat: 24g, Saturated Fat: 3g, Polyunsaturated Fat: 10g, Monounsaturated Fat: 9g, Sodium: 810mg, Potassium: 341mg, Fiber: 4g, Sugar: 6g, Iron: 3mg