Preheat oven to 400 degrees.
Line a baking sheet with parchment paper and drizzle oil lightly as a base layer.
In a small bowl, using fork, smash together butter and ginger. Set aside.
In a cast iron skillet over medium heat, warm 3-4 tablespoons olive oil. Add onion and bok choy, cut side down, and sear until golden brown, 2-4 minutes per batch (you may need to do a few batches pending pan size).
Turn bok choy cut side up. Add La Crema Sonoma Coast Chardonnay. Allow to cook for 2 more minutes and then pull from heat.
Layer enough bok choy and onion mixture evenly on parchment to cover the base of the fish for cooking; season with salt and pepper.
Rinse whole fish and season with salt and pepper. Set on bok choy bed. Using a spatula, spread the ginger butter inside the cavity of the fish generously. You will have leftovers. Add fresh cilantro.
Drizzle skin with olive oil to coat any leftover pan drippings. Place in oven.
Bake until fish is just cooked through, 15-25 minutes (depending on size).
Lay fish whole on platter and garnish with sesame seeds, cilantro and lemon. Use a knife to flake flesh off the bone