Heat oil in a large soup pot over medium heat. Add onions and sauté until soft and translucent, about 6 minutes. Add garlic and cook for 2 more minutes. Add carrots, celery, squash and cook, stirring often, until vegetables are soft, about 10 minutes.
Add lentils, split peas, stock, salt, and pepper and bring to a boil, reduce to a simmer, partially cover, and cook until legumes are soft, about 40 minutes. (Or INSTANT POT 20 MIN HIGH PRESSURE, quick release)
Place about 3 cups of soup in a blender. Process until smooth and add back to the pot and stir to combine. Stir in the kale and simmer for five minutes. Turn the heat off, adjust the seasonings, and add lemon juice.
Serve in bowls with a sprinkle of parmesan cheese.
