Boil lentils in salted water according to directions. Drain once soft.
In a deep pot or dutch oven, add olive oil and onion. Cook for 5 minutes.
Add salt, oregano, soy sauce, mushrooms, and turn the heat to medium high. Cook until mushrooms have some color.
Add the carrots, bell pepper, garlic, and 1/3 cup of water to the pot. Cook for 5 more minutes and salt again.
Add tomato paste and cook for 5 more minutes.
Add crushed tomatoes, parsley, 1/2 cup of water, walnuts, and the cooked, drained lentils.
Turn the heat down to medium-low and simmer for about an hour.