Preheat your oven to 425°F (220°C) to ensure a hot environment that crisps vegetables beautifully and caramelizes the miso glaze into a rich, sticky coating.

Chop carrots, bell peppers, broccoli florets, red onion, and zucchini into uniform pieces (~1") for even roasting. Drizzle with oil, season with salt and pepper, then mix well.

In a medium bowl, vigorously whisk white miso paste, soy sauce, honey, rice vinegar, minced garlic, and sesame oil until smooth, adding water as needed for a pourable texture.

Arrange seasoned vegetables on a rimmed baking sheet. Pour miso glaze over top, then gently toss with tongs or a spatula until every piece glistens with sauce.

Bake for 20–25 minutes, tossing once halfway, until vegetables are tender, lightly charred at the edges, and the miso glaze is sticky and golden brown.

Transfer traybake to a serving platter. Sprinkle toasted sesame seeds and chopped spring onions for a fresh, nutty crunch and vibrant color pop.