Heat oil in a pot. Add chopped onion and cook until it starts turning brown.
Add minced garlic and saute for a few seconds.
Add tomato paste, dried thyme, oregano, red chili flakes, and black pepper. Mix everything and saute for 1-2 minutes.
Next, add mushrooms and cook until the moisture released from mushrooms dries up.
Add lentils, mix and cook for about a minute.
Add chopped tomatoes with basil, vegetable stock, balsamic vinegar, and salt.
Cook until the vegetable stock starts boiling.
Break lasagna sheets into bite-size pieces and add to the soup. Cook for around 8-10 minutes or until the lasagna sheets are cooked.
Finally, add baby spinach and cook until the leaves get wilted, and then switch off the stove.
Garnish with fresh parsley. You may also add vegan cheese on top.
Enjoy your comforting vegan lasagna soup.