Pour the vegetable stock in a saucepan and bring to a light simmer. Heat the olive oil in a heavy saucepan over medium heat. Add the onion and sea salt and cook, stirring, until softened, about 5 minutes. Add the carrots, turnips, parsnips, and celery root. Cook for an additional 3-4 minutes. Add the arborio rice, tomato paste, ginger, and garlic and cook while stirring for 2 minutes, until the tomato paste is getting darker and fragrant.

Add 1 cup of the stock and stir, adjusting the heat to ensure the rice simmers nicely. Keep cooking and stirring until the stock has been absorbed. Keep adding stock with a ladle, about 1/2 cup at a time, and stir while cooking until each addition is absorbed. Repeat this process until the rice is tender but still has a bite. The whole cooking process should take about 25-30 minutes.

Once cooked, stir in the butter and season generously with pepper. Serve garnished with fresh parsley. Bon appétit!