Brown the ground beef in a large skillet over medium heat, breaking it up as it cooks until no pink remains.
Stir in the taco seasoning and water, then simmer for 5 minutes until the mixture thickens slightly.
In a large serving bowl, spread the shredded lettuce across the bottom to form the first layer.
Spoon the seasoned beef evenly over the lettuce.
Add the rinsed black beans in an even layer, followed by the diced tomatoes.
Sprinkle the shredded cheddar cheese over the tomatoes.
Top with the corn chips right before serving so they stay crisp.
Serve with sour cream on the side for guests to add as desired.