Preheat the oven to 425°F and line a large baking sheet with parchment paper. Place the sweet potatoes on the baking sheet, drizzle the olive oil and season with salt and pepper. Toss to combine and roast in the oven until golden, about 25-30 minutes.
To make the dressing, combine together the olive oil, balsamic vinegar, mustard, salt and pepper in a small bowl and whisk until well blended.
Place the Brussels sprouts and pecans in a large serving bowl. Add the dressing on top and toss to combine. Add the roasted warm sweet potatoes and crumbled blue cheese on top of the tossed salad, and serve immediately or refrigerate and serve cold.
Notes
Storage: Store any leftovers in an airtight container. They will last about 3-4 days in the fridge. Make Ahead Tips: You can make the dressing up to 3 weeks in advance and double or triple the recipe to have it on hand for other salads or even as a marinade.