In a skillet, brown the ground beef over medium heat until fully cooked.
Drain excess fat from the skillet.
Add taco seasoning and water to the skillet.
Stir well and bring to a simmer for 5 minutes.
While beef is simmering, warm the tortillas in a separate pan.
Once beef is ready, remove from heat.
Place a spoonful of beef mixture onto each tortilla.
Add shredded lettuce on top of the beef.
Sprinkle diced tomatoes and shredded cheese over the lettuce.
Top with sour cream and avocado slices before serving.