Grill-Steamed Sea Bass with Citrus Relish Recipe

Ingredients

• 2 1 1/2-pound whole black sea bass, cleaned
• Kosher salt
• Freshly ground black pepper
• 1/2 small red onion, thinly sliced
• 1/2 bunch flat-leaf parsley, plus 1/2 cup chopped
• 8 sprigs oregano
• 5 scallions, thinly sliced, divided
• 2 lemons, 1 thinly sliced, 1 left whole
• 2 limes, 1 thinly sliced, 1 left whole
• 4 tablespoons olive oil, divided
• 1 tablespoon chopped fresh tarragon
• 1/4–1/2 teaspoon crushed red pepper flakes
• Pinch of sugar
• 2 tablespoons walnut or pistachio oil
• Flaky sea salt (such as Maldon)
• 1 teaspoon poppy seeds