Brown the hamburger with onions. Mix in the water, salsa and taco seasoning and cook until thickened. Roll out the biscuits to 6 inch circles and spoon hamburger mixture onto them. Top each with a tablespoon of cheese. Fold up the biscuit edges; press to seal. Bake at 375 for 9-14 minutes or until golden brown. Serve with sour cream and/or salsa.