This vegan vegetable crumble is a delicious way to use up leftover root veggies. It is cooked in a fantastic mushroom onion gravy and tastes fantastic.
Peel the onions for the onion gravy, then cut them in half lengthways and slice them into 5mm (¼") half-moon shapes.
Heat the oil for the gravy in a medium 18cm or 7-8" (not nonstick) and over a low-medium heat.
Add the onions to the oil and cook for 45 minutes, stirring every 10 minutes or so. When the onions are cooked, they should be nice and golden.
Peel the parsnip, celeriac and swede and cut them into 1½cm (½-¾") cubes.
Cut the carrots into 1cm (½") thick rounds.
Cut the potatoes into 1½cm (½-¾") chunks.
Bring a 20cm or 8" saucepan of generously salted water to the boil, then parboil the parsnip, celeriac, swede and carrots.
Add the potatoes to the pan with the vegetables and parboil for another 10 minutes.
Mix together all of the ingredients for the crumble in a bowl and set aside.
15 minutes before the onions are ready, bring the vegetable stock to a boil, then reduce the heat to very low.
Add the dried mushrooms to the stock and allow them to sit for 10 minutes.
2 minutes before the onions are ready, add the tomato puree and cook for 2 minutes, stirring regularly.
Blitz the stock and dried mushroom mix in a blender, then strain it through a fine-mesh sieve into the onions.
Stir in the marmite and molasses into the gravy and simmer for 3-4 minutes.
Build the crumble by separating the parboiled veg between two 500-600ml (2-2½ Cup) baking dishes, then add the cauliflower florets, add 250ml (1 cup) of gravy to each dish, then top with the crumble.
Place the crumbles in the oven and cook for 45 minutes at 160°C or 302°F.
Reheat the remaining gravy and use it to serve on the side with the crumble.