Mix ground beef, onions, and taco seasoning mix in a bowl. Shape into 4 hamburger patties.
Cook patties in a large skillet over medium heat until no longer pink in the center, about 4 minutes per side. An instant-read thermometer inserted into the center should read at least 160 degrees F (70 degrees C). Drain fat and wipe the skillet with a paper towel.
Mix soup and water in a bowl. Pour over patties in the skillet; simmer until soup mixture is heated through, about 5 minutes. Mix in tomato, Cheddar cheese, corn chips, and olives. Scoop out the taco burgers and serve once cheese has melted.