Preheat the oven to 425°F (220°C) and line a baking sheet with parchment paper.

In a mixing bowl, combine brussels sprouts, carrots, sweet potatoes, and red onion. Toss well to mix.

In another bowl, whisk together olive oil, maple syrup, Dijon mustard, garlic powder, salt, and black pepper until smooth.

Pour the dressing over the vegetables and toss to coat evenly.

Spread the coated vegetables onto the baking sheet in a single layer.

Roast in the oven for about 25-30 minutes, stirring halfway through, until tender and caramelized.

Remove from the oven and allow to cool for a few minutes.

Garnish with fresh herbs if desired before serving.