Preheat your oven to 400ºF/200ºC.
Wash and trim the root off the Brussels sprouts. Discard any outer leaves that are wilted and then cut them in half or quarters if they're large. Transfer them to a sheet pan (no parchment paper needed). Add a drizzle of olive oil or avocado oil, and season with the garlic powder, salt, and freshly cracked black pepper. Toss with your hands to coat, then arrange them in a single layer with the cut side face down.
Bake them for 20 minutes. Flip them over so the crispy side is up.
Trim the woody ends off the asparagus and cut each spear into roughly 2-inch pieces, about 3 pieces per spear. Toss the cut asparagus with a little olive oil, kosher salt, and freshly cracked black pepper. Carefully arrange them amongst the Brussels sprouts and cook for an additional 5-7 minutes until lightly warmed through but still have a bright green color, with a crunchy, al dente texture.
Make the dressing by whisking all the ingredients together in a small bowl. Season to taste with salt and black pepper.
Toss the roasted vegetables with the vinaigrette and serve.