When steamed, these mussels release a briny broth seasoned by Shaoxing wine and aromatics, which can be sopped up with thick slices of buttered toast. But it's the homemade XO sauce, a seafood condiment from Hong Kong, that makes this one-pot dinner a dazzler.
XO Sauce: In a saucepan over medium heat, add both oils and heat to 200 F. Turn heat off and stir in gochugaru and cayenne pepper. Continue stirring for about 1 minute to fully infuse the oil, then let it steep another 1–2 minutes. To the infused oil, add fried shallots, fried garlic, and adobo; stir to combine. Cool and reserve at room temperature. Makes about 2 cups. (XO Sauce can be stored in an airtight container at room temperature for several days.)
Toast: Heat skillet over medium heat and add butter. When melted, foamy, and slightly brown, add bread slices in an even layer and toast, about 1 minute on each side. While bread is toasting, thinly slice the garlic cloves and set aside.When bread is toasted on both sides, remove from heat and set aside.
Mussels: In cold, dry pot (or Dutch oven), add garlic and bay leaves. Slice white and light green part of the scallions into 2-inch batons and add to the pot. Thinly slice about half of the green scallion stalks on a bias and set aside for garnish. To the pot, add sesame oil; turn heat to high. Stir, then sweat vegetables until soft and lightly brown, 3–4 minutes. Meanwhile, check mussels and remove any beards still attached with a firm tug. Mussels should be tightly closed. Tap any open ones; if they don’t close, discard. Add mussels to the pot and stir well to coat with the oil; then add the wine. Cover and let steam for about 1 minute. Check to see that the mussels are opening; stir again, and cover to steam for an additional 30 seconds to 1 minute.
Assembly: Cut bread slices in half and arrange against the sides of a serving bowl. Turn off heat; stir a ½ cup XO Sauce into mussels. Cover and shake the pot to emulsify sauce with cooking liquid. Add mussels, including the sauce, to serving bowl around the bread slices. Garnish with lime zest, sliced scallion greens, shichimi togarashi, and lime half before serving.
Simmer garlic in the olive oil over low heat until tender and lightly brown, 10 minutes. Strain, discarding garlic.
Finely chop 6 garlic cloves. Pour garlic oil into a shallow pan. Set pan over high heat until bubbly, about 2 minutes. Add chopped garlic, immediately turn heat to low, and cook 3–4 minutes, stirring the entire time to prevent garlic from burning. Strain fried garlic, reserving garlic oil, and proceed with recipe.)