Fry off the onion and mushrooms in olive oil and salt until all the steam has subsided, about 10 mins.
Add the garlic, sundried toms and smoked paprika. Fry 3 mins more, then add the tom puree and cook for an additional 3 mins.
Add the tomatoes, lentils, walnuts and a large pinch of salt and pepper. Break the tomatoes up with your spatula or a fork. Don't add too much salt here as you'll be adding some salty pasta water.
Simmer the sauce on low whilst you cook the pasta minus 2 mins of its packet instruction cooking time. Add the pasta directly into the sauce with a ladle, so you get lots of lovely salty pasta cooking water. Season to taste, you shouldn't need much. Reserve an additional mug of pasta water to stir in later if you're not eating straight away.
Serve with cashew parm, extra virgin olive oil and cracked black pepper.
