1. Preheat oven to 190°C (375°F).

2. Divide the tuna, ginger, rice vinegar, and half the green onions onto four sheets of aluminum foil. Close each into a tightly sealed papillote and bake in the oven about 20 minutes.

3. At the end of cooking, blanch the bok choy for just a few minutes.

4. In a saucepan, bring the vegetable broth to a boil, add soy sauce, and simmer for 2 or 3 minutes.

5. Divide the bok choy onto 4 plates. Place the tuna steaks on top, garnish with remaining green onions, and pour sauce over the tuna.

6. Drizzle with sesame oil and serve with vermicelli noodles.

Aide-gourmet tip: Replace tuna with pork tenderloin and reduce oven temperature slightly to 180°C (350°F).