Preheat oven to 400°F.In a large pot add first listed water and salt, bring to a boil, add pasta, stir as needed, and cook 8-11 minutes until al dente. Drain, rinse, and reserve. Meanwhile, place lentils and second listed water in a pot and boil for 15-17 minutes, drain, and reserve.
Toss the mushrooms in the first listed olive oil and roast in oven for 20 minutes. Then, add mushrooms to a food processor and blend until a finely chopped paste is formed.
To a large skillet, add second listed oil and heat over medium heat. Add onions and garlic and cook for 2-3 minutes until onions are translucent and garlic is aromatic.Add walnuts, mushrooms, and cooked lentils. Brown and warm through. Add cumin, coriander, nutmeg, paprika, and salt and cook for 2 minutes until aromatic.Add tomato paste and cook for 5 minutes, stirring to fully combine.Add vegetable stock, tomato puree, and oregano. Cook for 25-30 minutes to allow all flavors to develop.