In dutch oven or soup pot, warm the olive oil over medium heat, add the onion, carrots and celery, and cook, stirring often with a wooden spoon or spatula, until vegetables have softened and onions begin to turn translucent, 5–10 minutes. Add the tomato paste, stir and cook for a couple more minutes.
Add the seasonal vegetables and lentils (if using), garlic, spices and cook, stirring, a couple minutes until fragrant. Add the tomatoes, broth, water and bay leaves. Increase heat and bring to a boil then lower heat to maintain a gentle simmer, partially cover with lid (leave a gap for steam to escape), and cook for 15 minutes.
Uncover and add the pasta, beans and kale. Continue simmering uncovered until the lentils are tender and the pasta is al dente, about 20 minutes longer.
Turn off the heat, remove and discard the bay leaves, and squeeze in a couple teaspoons of fresh lemon juice. Stir and ladle into warmed serving bowls. Pass the freshly grated Parmesan, black pepper and flake salt.