Pre-heat the oven to 180°C/350°F/gas mark 4.
Peal and cut the carrots and parsnips in cubes and set aside. Mince the onion and the shallots and set aside separately. Cut the seitan in cubes and the mushrooms in quarters and set aside separately.
Cut each red kuri squash in two and scoop out the seeds and fibers. Oil an oven dish and put in the red kuri squash halves. Cook in the oven for 25 min.
In a saucepan with some oil, gently fry the onion and shallots on medium heat until softened. Stir in the seitan, the mushrooms, the bay leaves, and one branch of rosemary. Pour in the red wine. Add the tomato purée, the mustard, and the vegetable stock. Cook for 45 min.
In the meantime, glaze the carrots and parsnips separately before adding them to the wine sauce to finish cooking. To glaze the carrots, lightly sauté them in a pan with some oil, add a teaspoon of sugar, shake the pan, and let cook for about a minute. Then, add the carrots to the wine sauce. Repeat for the parsnip.
When the wine sauce and vegetables are done, you have finished your bourguignon! Place a red kuri squash half on a plate and serve the bourguignon in the center. Garnish the bourguignon with the remaining fresh rosemary.