Preheat your oven to 450°F and place two baking sheets inside to heat while you prep. Trim the brussels sprouts and halve them lengthwise, then toss them in a bowl with the olive oil and a generous pinch of kosher salt until evenly coated. Divide the sprouts between the two hot baking sheets, arranging them cut-side down—this creates the golden, caramelized surface that makes this dish shine. Roast for 15–20 minutes, swapping the pans halfway through so they cook evenly. The sprouts are done when the cut sides are deeply browned and the outer leaves are crispy.

While the sprouts roast, combine the Worcestershire sauce, ketchup, honey, rice vinegar, minced ginger, and shichimi togarashi in a small pot. This combination creates a deeply savory, slightly sweet, and gently spiced glaze that's the heart of the dish. Bring the mixture to a simmer over medium heat and let it bubble gently for 3–4 minutes, stirring occasionally, until it thickens slightly and the flavors meld together. Taste and adjust the salt as needed—I find that a pinch or two really brings out the umami depth without making it salty.

Transfer the roasted brussels sprouts from the baking sheets to a large mixing bowl. Pour the umami glaze from Step 2 over the hot sprouts and toss gently but thoroughly until every piece is coated with the glaze. The heat from the sprouts will help the glaze cling to them beautifully. Transfer the glazed sprouts to a serving platter, arranging them in an attractive mound or spread.

Now comes the fun part—building layers of texture and flavor on top. Scatter the nori strips over the sprouts first, then drizzle generously with Kewpie mayonnaise (I prefer Kewpie because it has a richer, more egg-forward flavor than American mayo). Pile the bonito flakes in the center—they'll continue to curl and wave from the residual heat, which looks stunning. Finally, sprinkle with the toasted sesame seeds and sliced scallions, then finish with a light dusting of shichimi togarashi. Serve immediately so the bonito flakes maintain their delicate texture.