Heat a large skillet with avocado oil. Once hot, add in onions, carrot, celery, and pepper. Let cook 5 minutes, stirring often.
Add in garlic, salt, pepper, oregano, basil and red pepper, and let cook an additional 2-3 minutes or until veggies are starting to soften.
Add in the lentils, water, diced tomatoes, and balsamic vinegar and stir.
Bring to a boil. Once boiling, lower heat to medium and cook for 40-45 minutes or until all liquid is absorbed and lentils are cooked.
Serve over pasta, spaghetti squash, or with bread.