1. Get the lentils ready by soaking them in some water for at least half an hour. While the lentils soak, focus on other parts of the meal and prep the ingredients.
2. Heat some olive oil in a big pan. Once the oil is nice and hot, add some diced onions and sprinkle lightly with salt. Stir the onions regularly, cooking them until they brown slightly. Add some water to dissolve all the yummy bits at the bottom of the pan, then keep cooking the onions while you add more water and stir constantly to avoid burning. Keep going until the onions are soft and nicely browned.
3. Toss in the garlic, thyme, oregano, salt and pepper according to your preference. Cook for a minute or two, stirring frequently.
4. Add the tomato paste and cook for a few minutes. Stir regularly until the paste turns a darker shade of red.
5. If you're using some red wine, now's the time. Pour it in and let it cook, scraping up any bits that have stuck to the pan. Keep cooking for another minute or two, or until the alcohol smell is gone.
6. Pour in the broth, dissolving any brown bits at the bottom of the pan. Stir in the tomato paste and add the lentils and walnuts. Mix everything well. Bring to a boil, then reduce the heat to medium-low and simmer for a good 20 minutes, stirring once in a while.
7. Add the crushed tomatoes and simmer for another 15-20 minutes until the lentils are tender but still have a little bite to them. Stir every now and then to make sure nothing burns or sticks. Depending on whether you're using crushed or whole tomatoes, you may need to add water or lower the heat to avoid burning.
8. In another pot, boil some water and add salt. Cook the pasta until it's almost al dente. Save some of the pasta water just in case you need it later. Drain the pasta, but don't rinse it.
9. Taste the bolognese and add more salt and pepper if needed. Finish off with some balsamic vinegar.
10. Combine the hot pasta and the bolognese, tossing everything together. Add a little bit of pasta water if the sauce is too thick. Top with parsley or basil if you like.