Grab 30 Day Vegan Diet Challenge From Here :

2 cups broccoli or broccolini florets only,
2 cups halved Brussels sprouts,
1 medium-large sweet potato,
cut into 1-inch pieces (about 2 cups),
1 can (14-ounce) chickpeas (drained, rinsed),
olive oil (or lemon juice for oil free),
garlic powder,
salt and freshly ground black pepper.

For the dressing:
½ cup Dijon mustard,
½ cup tahini,
½ cup water,
¼ cup apple cider vinegar,
2 tablespoons maple syrup,
or to taste,
2 tablespoons freshly squeezed lemon juice,
Salt and freshly ground black pepper to taste.

Preheat the oven to 400°F. Line a large baking sheet with parchment paper or use a non-stick sheet. Set aside.
Transfer the broccoli, Brussels sprouts, and sweet potato, and chickpeas to a medium bowl. Toss with just enough olive oil (or lemon juice) to give the vegetables a slick, glossy coating. Add the garlic powder, salt, and freshly ground black pepper and use your hands to rub the vegetables with the oil and seasonings.
Transfer the vegetables to large baking sheet.
Roast for 15 minutes before tossing the vegetables. Roast for about 5 minutes more, or until the sweet potato is just tender.
Change the oven setting to broil and cook for about 2 minutes more, or until the Brussels sprouts are slightly charred.) Transfer the roasted vegetables to a large bowl.
In a medium bowl, whisk the Dijon mustard, tahini, water, apple cider vinegar, maple syrup, and lemon juice until combined. Adjust maple syrup to taste. Add salt and freshly ground black pepper.
Add the desired amount of dressing to the roasted vegetables and stir to coat. Refrigerate any remaining in an airtight container for up to 5 days.