Before you start, preheat oven to 160°C.
Prep mushroom and veggies. Place dried mushrooms in a heat-proof bowl and cover with boiling water to measure. Leave to hydrate for 10 minutes. Remove mushrooms from liquid (reserve liquid) and finely chop. Meanwhile, prep remaining ingredients.
Cook mushrooms. Heat a drizzle of oil in an oven-proof pot or casserole dish (with a lid) on high heat, fry mushrooms for 2-3 minutes, until browned. Remove mushrooms from pot and return pot to medium heat.
Cook ragù. Add another drizzle of oil to pot. Cook onion, garlic, carrot, celery and thyme for about 8 minutes, stirring, until softened. Add tomato paste, spiced and yeast flakes and cook for 2 minutes, stirring, until fragrant.
Add the tomato, browned mushrooms, soaked porcini mushrooms and soaking liquid, wine and salt to pot and bring to a simmer. Once simmering, cover pot with a lid and transfer to pre-heated oven. Bake for 1 hour.
After 1 hour of baking, remove lid from pot and return to over for a further 25 minutes, until the sauce has reduced and thickened. Lightly crush mixture with a masher to achieve a ragù-like consistency. Season to taste with salt and pepper.