Heat the oil in a large pan over a low heat. Add the onion, celery and carrot and cook gently, stirring often, for 10-15 minutes until soft.
Add the finely chopped mushrooms and garlic, turn up the heat a little and continue to cook until all of the excess liquid has evaporated.
Add the tomato puree and smoked paprika and cook for a minute, then add the red wine and cook until almost all of the liquid has evaporated.
Add the sun dried tomatoes, oregano, thyme, rosemary, bay leaves, soy sauce, tinned tomatoes, stock, sugar, lentils and walnuts.
Bring up to a gentle simmer and cook for 40-50 minutes, stirring every now and again, until the lentils are tender. You can add a splash of water or stock if it becomes too thick.
Add the nutritional yeast and a good grinding of black pepper, season to taste with salt and serve with pasta.
Notes
See post above for tips, details and step-by-step photos.