Begin by cooking your pasta of choice according to its package directions. Given amount makes about four servings.
Next, add the onion, garlic and water to a pot over medium heat. Cook them until the onion begins to soften and the water evaporates. Then add the oregano, salt and red pepper flakes. Cook for another minute.
Add the lentils. Stir them in along with the tomato paste. Add the vegetable broth, tomato sauce and half of the balsamic vinegar. Mix well. Bring the sauce to a gentle boil. Then reduce the heat and simmer for 30 minutes or until the lentils are very tender.
Finally, stir in the remaining balsamic vinegar and continue to simmer for an additional 2-3 minutes. Season with additional salt, if needed.