Preheat the oven to 425F. Arrange the prepped veggies and sausage on a large baking sheet in one even layer. Drizzle with the olive oil and sprinkle with the salt.
Place the pan in the oven and roast for about 40 minutes total, stirring every 10 minutes or so (2-3 times during the roasting).
While the veggies are roasting, make the dressing by whisking or shaking the lemon juice, olive oil, mustard, salt, sugar, and garlic together.
When the veggies are tender and the sausage is crispy at the edges, scoot them to one half of the baking sheet and pile all of the spinach onto the other side of the baking sheet. Turn the heat on the oven OFF. Drizzle about half of the dressing over the spinach.
Place the sheet pan back in the oven for about 2 minutes, just to barely wilt the spinach. Toss the spinach to evenly coat in the dressing, then divide the spinach, sausage, and veggies onto plates. Drizzle with extra dressing if you'd like. Enjoy!
Notes
For Meal Prep, you can chop all of the veggies and make the salad dressing. I like this as leftovers but it's definitely better right out of the oven - eat it freshly cooked once if you can!You can swap out any root vegetables, potatoes, or squashes you'd like! Choose hearty veggies that will hold up to the heat.I cut everything into about 1-inch chunks, but as long as things are relatively similar in size they'll cook evenly.I used quantities for the veggies in this recipe, but you really want enough sausage and veggies to evenly coat one large sheet pan. Add more or less based on what you have and how big your pan is!This recipe is gluten free as written, and would be vegan if you used a vegan sausage substitute. YUM.