I have been making this recipe for several years. I originally found it on a website for preschool operators--apparently preschoolers like their lentils. However, not to be content with a simple and fat-free recipe, I've modified it to suit my taste.
1. Heat the oil over medium-low heat. Add the asofoetida if using and wait for it to sizzle. Add the carrots and mushrooms and cook for about five to ten minutes, until the mushrooms release their juices and the carrots start to stick a little to the bottom of the pan. Add the nutritional yeast (if using) and cook for another minute or two, until the yeast starts to contribute to the browning.
2. Add the tomato sauce, broth and lentils. If you have tomato paste handy you can add another tablespoon or two for added flavor. Bring to a boil and then reduce the heat to very low. Cover and simmer for about 40 minutes or until the lentils are tender.
3. Add the pasta and cook for another ten minutes or so until the pasta is tender. The pasta continues to cook even after you turn off the heat, so don't overcook. Season with salt and pepper to taste and add a tiny drizzle of olive oil when serving.
This makes a great weeknight supper. I usually make it the night before and reheat it.