Bring water, tomato sauce, taco seasoning and lentils to a boil. Turn heat to medium-low, cover pan, and simmer for 15-20 minutes, or until lentils are tender and liquid is absorbed.
While lentils are cooking, prepare the avocado sauce, by mashing the avocado with the juice of 1 1/2 limes and salt. Use the remaining lime juice to drizzle the cabbage with.
Also, char the tortillas. I put them directly over my gas burners (over medium-heat) for 1 minute per side, but you can also heat them in dry hot skillet the same way.
To assemble, place a layer of cabbage on tortilla, top with lentil mixture, diced tomatoes, cilantro and a drizzle or dollop of the avocado cream.