Heat a large skillet over medium-high heat. Add ground beef and cook, breaking it apart with a wooden spoon, until browned and cooked through, about 6-8 minutes.
Drain any excess fat from the pan. Add taco seasoning and water, stirring to combine. Simmer for 3-4 minutes until the mixture thickens slightly.
While beef is cooking, warm tortillas in a dry skillet for 30 seconds per side or wrap in damp paper towels and microwave for 20-30 seconds.
Assemble tacos by dividing beef mixture evenly among the 8 tortillas (about 1.5 oz per taco).
Top each taco with lettuce, tomatoes, cheese, a dollop of Greek yogurt, and fresh cilantro if desired. Serve immediately and enjoy!