Heat oven to 350°F. Spray 9x5-inch loaf pan with cooking spray.
In 12-inch skillet, cook ground beef with taco seasoning mix over medium-high heat, stirring occasionally, until thoroughly cooked; set aside.
Separate each can of dough into 8 biscuits; cut each into quarters. In large bowl, toss biscuit pieces with cooked ground beef and Cheddar cheese. Pour into loaf pan.
Bake 35 minutes or until dark golden brown.
Meanwhile, in medium bowl, toss tomato, onion, avocado, cilantro, lime juice, salt and pepper.
Cool bread in pan 5 minutes. Place lettuce on serving plate. Invert bread onto plate over lettuce.
Top with sour cream and tomato-avocado mixture. Serve immediately.