Heat oven to 400 degrees. Line a large baking sheet with silicone or parchment.
Prep cauliflower, carrots, and onions, adding each to the baking sheet as you finish. Drizzle with olive oil and toss to coat veggies.
Mix remaining ingredients, except lime if using, into a small bowl. Sprinkle over vegetables and toss again to evenly coat them.
Roast for 25-30 minutes, stirring at the halfway mark, just until a fork just pierces the largest pieces (aim for firmer vs. softer).
Remove from oven and squeeze the half lime over all the veggies (if using), tossing again before serving.
Notes
Make Ahead: This dish can be made 2-3 days ahead and stored in the fridge. Gently reheat for 5-10 minutes in a 350 degree oven.Storage: After serving you can store this in an airtight container in the fridge for a week, making it a great meal prep option with grilled chicken or sausage.Reheating: Heat in the microwave for about a minute, stirring halfway through or warm in a toaster oven sheet pan or regular oven for 5-10 minutes.Freezing: I haven't tried freezing this, but roasted veggies typically freeze well. I would roast only 20-25 minutes to make sure they are still firm before freezing. Thaw before reheating.