In a large pot of salted boiling water, cook soba noodles and edamame until tender but still firm. Drain and gently rinse with cold water. Transfer to a bowl, add sesame oil and toss to coat.

In a blender, purée the orange juice, peanut butter, rice vinegar, lime juice, orange zest, tamari, garlic, lime zest and red-pepper flakes until smooth. Set aside.

In a skillet, heat the olive oil over medium heat until hot. Add the mushrooms and bok choy and stir-fry for 2 minutes. Add the bell pepper and stir-fry until softened, about 2 minutes.

In a large bowl, combine bok choy mixture, scallions, chopped cilantro and mint. Add dressing and noodles and toss gently to coat. Garnish with cilantro sprigs, additional scallions and sesame seeds, if desired.