Add the walnuts and sun dried tomatoes to the bowl of your food processor and pulse until broken down and crumbly, without pureeing. Transfer to a small bowl and set aside.
Now add the onion, garlic and cauliflower florets to your food processor and gently pulse until chopped, but again, do not over process. You want to keep the pieces chunky for a hearty sauce. Work in batches if needed. (I have a 14 cup processor and usually do two batches.) Transfer each batch to a sauce pot or deep non stick skillet.
Sauté the veggies over medium high heat, stirring occassionally, until softened, approx 5-7 minutes. You should not need water or oil, as the veggies will create their own moisture. But if things are starting to stick, add a 1-2 tablespoons of water or oil.
Now add all the remaining sauce ingredients: walnut and sun dried tomato mixture, tomato sauce, broth, lentils and all the seasoning. Simmer for 15-20 minutes, until lentils are cooked and sauce is thickened. Taste for seasoning and add more salt or oregano, if needed. Once cooked, discard the bay leaves.
Meanwhile, bring a large pot of generously salted water to a boil, and cook your pasta according to package directions for 'al dente' pasta. Then serve your pasta with a generous scoop of your Bolognese sauce on top.
Do not over process your veggies. You want a chunky, hearty cauliflower Bolognese sauce, so make sure not to overly process or puree the ingredients.For nut free, you may sub the walnuts for pumpkin seeds with similar results.Simmer the sauce for a longer time period, rather than boil for a shorter one. Simmering your sauce allows the flavours to marry beautifully. If you have extra time, simmer for even longer than the 20 minutes called for. The more it simmers, the more the flavours will amplify.Add more broth if your sauce gets too thick. It should be thick and rich, but if you find it's getting too thick while simmering, add another half to one cup of low sodium vegetable broth.Use more sauce if you want a "saucy-er" sauce. Traditionally, it is meant to be rich and thick though, so I recommend trying as is first.Add more veggies if you want even more flavour. Some great additions include mushrooms, carrots and eggplant. Just process them along with your other veggies into a crumbly texture.Cook your pasta 'al dente', do not over cook. Al dente translates as to be firm when bitten. Us Italians prefer our pasta with a little bite, and not too soft. Plus, the pasta will continue to cook and soften slightly once covered in your hot vegan Bolognese sauce, so it's always best to slightly under cook your pasta by about 1-2 minutes.For a low calorie diet, pasta is not always a calorie friendly choice. Use a smaller portion of pasta and a larger portion of your cauliflower Bolognese sauce. After all, that's where all the flavour is!