Spray counter lightly with non-stick cooking spray. Roll combined rolls or loaf into a 12x16-inch rectangle. Cover with plastic wrap and let rest.
Brown ground beef, onion and taco seasoning together and drain. Set aside to cool slightly. Stir tomatoes, cheese and olives into the meat mixture. Remove wrap from dough. Spoon mixture lengthwise in a 4-inch strip down center of dough.
Make cuts 1 1/2-inches apart on long sides of dough to within 1/2-inch of filling. Begin braid by folding top & bottom strips toward filling. Then braid strips left over right, right over left. Finish by pulling last strip over and tucking under braid. Lift braid with both hands and place on a large sprayed baking sheet. Cover with sprayed plastic wrap and let rise 30 minutes.
Remove wrap and bake at 350°F 30-35 minutes.
Serve warm with sour cream and salsa, if desired.