Heat the olive oil in a skillet over medium heat.
Add diced onion and sauté until translucent, about 3 minutes.
Stir in the minced garlic and cook for an additional minute.
Add the ground beef to the skillet, breaking it apart with a spatula, and cook until browned, about 5-7 minutes.
Drain excess fat if necessary.
Stir in the taco seasoning and water. Bring to a simmer and cook for about 5 minutes until thickened.
While the beef simmers, prepare your taco shells or tortillas by warming them in the oven or microwave.
Assemble the tacos by spooning the ground beef mixture into each taco shell.
Top with shredded lettuce, diced tomatoes, cheese, sour cream, and salsa.
Add any additional toppings you desire, such as jalapeños, cilantro, or avocado.