Heat the oil in a dutch oven or other heavy bottomed soup pot over medium-high heat. Add the onions and cook until softened, about 5 minutes, then add the carrots, and cook another 5 minutes, giving everything a stir now and then.
Add the garlic-salt mash and stir fry for a minute or two. Add the tomatoes, water (I just fill up the big tomato can twice and dump it in), lentils, farro, Worcestershire sauce, bay, thyme, and black pepper. Bring to a boil, then lower heat to a slow simmer and cook for an hour. (At some point, if you've used whole tomatoes, snip at them with a pair of kitchen sheers to cut them into chunks, quarters is good enough.)
Before serving, remove the bay leaves and stir in the mustard and vinegar. Top with a few parmesan croutons. Enjoy!
While soup is cooking, preheat oven to 375° F. Tear a day or two old chunk of sourdough into bite-sized pieces (about 1″) and put the pieces in a bowl. For about 6 cups of bread pieces, use 6 tablespoons of oil and toss with your hands to soak up the oil. Sprinkle in 2 tablespoons shredded Parmesan and toss. Transfer to a rimmed sheet pan and bake for 15 minutes until golden brown and crispy.