Easy Taco Casserole

Name: Easy Taco Casserole
Ingredients: 1 pound lean ground beef or ground chuck; 1 ( 1 - ounce ) envelope taco seasoning mix; 1 medium red onion , finely chopped, divided; 2 cups mild chunky salsa; 1 ( 15 - ounce ) can black beans, drained and rinsed; 4 cups sturdy tortilla chips (about 3 1/2 ounces ); 4 ounces pre-shredded Mexican 3-cheese blend (about 1 cup); 1/2 cup shredded iceberg lettuce; 1/2 cup chopped tomatoes; 1/3 cup sour cream