In a glass baking dish, combine maple syrup, 1 tablespoon low-sodium soy sauce, sesame oil and crushed red pepper; add cod fillets and coat in sauce. Refrigerate 30 minutes to 2 hours. Transfer fish to a foil-lined baking sheet. Roast at 475° until cooked through and slightly browned (9-10 minutes). Meanwhile, heat canola oil in a large skillet over medium-high heat; add minced garlic and ginger and cook, stirring, until fragrant (1 minute). Add bok choy, mirin, 1 tablespoon low-sodium soy sauce, and vinegar, and cook, stirring, until greens are wilted and stalks are tender-crisp (3-4 minutes). Divide bok choy and cod among 4 plates; sprinkle fillets with chopped scallion and toasted sesame seeds.