In a heatproof bowl, stir together the boiling water, rice vinegar, sugar, mustard seeds, and salt until the sugar dissolves. Add the sliced scallions, toss well, and let them rest at room temperature for about 30 minutes.

Rinse the jasmine rice under cold water until the water runs clear. Drain well.

In a medium saucepan, combine the rice, coconut milk, water, and salt. Bring to a boil, then cover, reduce heat to low, and simmer for 15-20 minutes until the liquid is absorbed and the rice is tender. Fluff with a fork and keep warm.

Preheat your oven to 425°F (220°C).

Place the sea bass fillets on a sheet pan. Drizzle with 1 tablespoon of olive oil and season with salt and black pepper. Roast for 12-15 minutes until the fish is opaque and flakes easily. Remove from the oven and keep warm.

In a large skillet, heat the remaining 2 tablespoons of olive oil over medium-high heat.

Add the onion, garlic, chili, and shiitake mushrooms. Cook for 4-5 minutes, stirring occasionally, until the mushrooms soften and start to brown.

Stir in the miso paste until smooth. Add in the coconut cream, rice vinegar, and sugar. Bring to a gentle simmer and cook for 7-8 minutes, stirring often, until the sauce thickens slightly.

Finish the sauce with chili oil, lime zest, and lime juice. Season to taste with salt and black pepper. Keep warm over low heat.

In another large skillet, heat 1 tablespoon of oil over medium-high heat. Place the bok choy cut-side down and sear for 7-8 minutes, turning once until lightly charred and tender. Season with salt and black pepper.

Spoon coconut rice onto plates, top with the roasted sea bass, and generously spoon the miso coconut sauce with mushrooms over the fish. Garnish with pickled scallions and serve with the seared bok choy on the side.