Preheat the oven to 425º F.
Place the sweet potato, red pepper, onion and mushrooms in a bowl. Toss the veggies with olive oil, salt, pepper and thyme until everything is evenly coated.
Place the veggies in a single layer on a large sheet pan. Put the pan in the oven and bake for 20 minutes, or until the sweet potato is tender.
While the veggies are cooking, you can prepare the dressing. Add the dijon mustard, honey, balsamic vinegar, salt and pepper to a bowl and whisk together. Then, slowly add the oil while whisking. Keep whisking until the oil is fully incorporated.
Once everything is done, you can build the salad. Place the spinach in a bowl, then top with the roasted veggies, feta cheese and pepitas. Drizzle the dressing over the salad and enjoy!
