Brown the ground beef in a large skillet over medium-high heat, breaking it up as it cooks, about 8-10 minutes.
Drain excess fat, then stir in taco seasoning and 1/2 cup water. Simmer for 5 minutes until sauce thickens.
Warm taco shells according to package directions, or wrap tortillas in foil and heat in a 300°F oven for 10 minutes.
Arrange all toppings in separate bowls and set out on a table or counter with serving spoons.
Place the warm meat in a serving dish and set out with the shells and toppings.
Let guests build their own tacos with their preferred combination of ingredients, squeezing lime over the top.