Step 1. Preheat the oven to 400 degrees.
Step 2. Heat the ground beef and onion in a skillet over medium-high heat until the meat is browned and the onion has softened.
Drain any excess fat.
Step 3. Reduce the heat to low and stir in the taco seasoning. Saute for a few minutes longer.
Step 4. Place one bag of tortilla chips on each of two different baking sheets, and top each set of chips with half of the refried beans.
Step 5. Sprinkle half of the meat mixture over each of the batches of chips, and separate the cheese evenly between the two baking sheets.
Step 6. Bake for 10-15 minutes until the cheese has melted.
Step 7. Sprinkle immediately with the chopped tomato and green onion and serve
