Rinse, drain, and inspect the lentils. Set aside.
In a large pot placed over medium heat, add the olive oil. Once the oil warms up, add the chopped onion. Stir to make sure that the oil fully coats the onion.
Cook the onions until they slightly soften. Then add the garlic, carrots, celery, and potatoes. Stir to combine.
Season with salt, pepper, paprika, and red pepper flakes. Stir to fully combine.
Add in the balsamic vinegar. This will help deglaze the pan. Stir to combine.
Next, add the rinsed lentils and vegetable broth. Stir to combine.
Allow the mixture to come to a boil. Once it comes to a boil, reduce the heat to low, cover, and allow it to simmer for 30-45 minutes or until the lentils and veggies are soft.
Serve immediately. You can top this with parsley, grilled onion, sour cream, chives, ham or even bacon bits!