To make the vegan gravy, heat the oil in a heavy based pot or pan on medium heat and add the chopped onion, celery and carrot. Sauté for around five minutes or until the onion is tender and beginning to brown at the edges a little. Add the smashed garlic.
Stir in the flour and cook for two minutes. Add the red wine to deglaze the pan and then add the Marmite. The mixture with be a little gluey, don't worry, it's normal. Add the fresh herbs.
Stir in the vegetable stock and water and continuing cooking for a further few minutes, stirring regularly, until the gravy thickens.
Add the butter and turn the heat to low. Cook for a further three minutes.
Remove from the heat and add a splash of apple cider vinegar and season well with salt and pepper.
Allow the gravy to sit for around 10 minutes to continue infusing the flavours before straining in to a gravy jug. If the gravy is too thick, add a splash of water to thin. Return to the pan to warm if needed before serving.
To prepare the potatoes, preheat the oven to 200 degrees C (400 degrees F) and place the potatoes in a large pot. Cover them with cold, salted water and bring to a boil. Reduce the heat and cook for around twenty minutes or until tender but firm.
Strain the potatoes and allow them to sit for five minutes to steam dry.
Place them on a large roasting tray and using a fork or masher, gently press down until they "smash". Break up the garlic and put it in the pan also. Drizzle well with olive oil and season with sea salt. Sprinkle with fresh thyme.
Roast in the oven for fifteen minutes before carefully removing them. Flip the potatoes over and return them to the oven for another fifteen minutes or until they are crispy.
Meanwhile, cream the miso paste and butter together to a soft whip.
Remove the potatoes from the oven and serve with a small dollop of miso butter.
Preheat the oven to 200 degrees C (400 degrees F). To prepare the roast leeks, lay the leeks side by side in a small roasting pan or oven proof tray.
Drizzle with olive oil and season well with salt and pepper. Add a few spoons of vegetable stock and roast for an hour, adding more stock intermittently to keep the leeks from drying out. If the leeks begin to brown while they are still firm, cover them with foil and continue to roast.
When soft and tender, sprinkle the leeks with parmesan to serve.