Seafood Soup With Ginger and Yuzu Kosho

Ingredients

• 1 tbsp. olive oil
• 6 scallions, white and light green parts very thinly sliced
• 3 garlic cloves
• 1 large shallot, thinly sliced, rinsed and dried
• 1 lemongrass stalk, trimmed, tender bulb parts very thinly sliced
• One 1-inch piece fresh ginger, peeled and very thinly sliced
• 1 thin slice red chile pepper
• 1 small strip lime zest
• Salt
• 1 tsp. tsp. red yuzu kosho
• 1⁄4 cup dry white wine or vermouth
• 5 cups chicken, fish, or vegetable broth
• Pinch of sugar
• 24 mussels, scrubbed
• 1 1⁄2 lb. skinless cod fillet, or other firm white fish
• 24 medium shrimp, peeled and cleaned
• 6 large, head-on shrimp, or substitute peeled
• 6 scallions, white and light green parts only, each cut crosswise into 3 pieces
• 2 large white or brown mushrooms such as cremini, trimmed and thinly sliced (preferably with a mandoline)
• 1 shallot, very thinly sliced, rinsed in cold water and strained
• 1⁄2 sweet potato (cut crosswise), peeled and thinly sliced (preferably with a mandoline)
• 1 handful baby spinach
• Lime wedges, for serving (optional)
• Chopped cilantro or seaweed flakes, for serving (optional)