Preheat your oven to 400. Toss the cauliflower, potatoes, and carrots in 3 tablespoons of olive oil, season with salt and pepper. Place the cauliflower on one baking sheet, the potatoes and carrots on another (they have different cooking times). In a saucepan, combine the rice and 2 cups of water. Bring to a boil, and then reduce to a simmer. Add the remaining tablespoon of olive oil and a pinch of salt. Cover and cook 50 minutes. Meanwhile, remove the cauliflower after about 25 minutes. Remove the potatoes and carrots after about 1 hour. After the rice is fully cooked, remove the pot from the heat, keep covered and let sit for 10 minutes. Fluff with a fork, season with salt and pepper. Serve a mound of rice topped with roasted vegetables, and enjoy!