Preheat your oven to 350°F (175°C).
In a skillet, cook the ground beef over medium heat until browned. Drain the fat.
Add the taco seasoning to the beef and stir to combine.
In a mixing bowl, combine the sour cream, mayonnaise, and half of the shredded cheese.
In a baking dish, layer the biscuits on the bottom.
Spread the beef mixture over the biscuits.
Top with the sour cream mixture, then add the chopped onions and diced tomatoes with green chilies.
Sprinkle the remaining shredded cheese on top.
Bake in the preheated oven for 30 minutes, or until the cheese is melted and bubbly.