Preheat the oven to 425°F (220°C). Line a large baking sheet with parchment for easy cleanup.
In a small bowl, whisk together the miso paste, maple syrup, soy sauce, rice vinegar, olive oil, sesame oil, and a pinch of salt and pepper until smooth.
Toss the cubed sweet potatoes and halved Brussels sprouts with half of the miso glaze. Spread them in a single layer on the baking sheet.
Roast for 15 minutes, then give the vegetables a good toss and brush with the remaining glaze. Return to the oven and roast for another 10-15 minutes, until the edges are caramelized and the vegetables are tender.
If you like a bit more color, turn on the broiler for 1-2 minutes at the end, watching closely so they don’t burn.
Remove from the oven, taste, and adjust with a pinch more salt if needed. Sprinkle with sesame seeds before serving.