Rinse jasmine rice thoroughly under cold water until water runs clear. Combine rice and water in a saucepan, bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes. Remove from heat and let stand, covered, for 5 minutes. Fluff with a fork.

In a small bowl, whisk together miso paste, mirin, sake (if using), soy sauce, sugar, and 1 teaspoon sesame oil until smooth to create the glaze.

Pat cod fillets dry with paper towels. Heat a non-stick skillet over medium-high heat with a drizzle of sesame oil. Place cod fillets skin-side down (if applicable) and cook for 3-4 minutes until the skin is crispy.

Flip the cod, then brush liberally with the miso glaze. Reduce heat to medium-low and continue to cook for another 3-5 minutes, brushing with more glaze, until the fish is cooked through and flakes easily. Be careful not to burn the glaze.

While the cod cooks, steam or quickly sauté the bok choy. In a separate pan, heat a little sesame oil over medium heat. Add bok choy and sauté for 3-5 minutes until tender-crisp. Alternatively, steam in a steamer basket for 4-6 minutes.

Serve the miso-glazed cod immediately over fluffy jasmine rice, alongside the tender bok choy. Garnish with a sprinkle of sesame seeds.