Preheat oven to 350 degrees. Heat vegetable oil in large skillet over medium heat and cook onion and garlic for 4 minutes or until softened. Add ground beef and cook for 4 minutes or until browned. Stir in taco seasoning and 1/4 cup water. Cook for 2 minutes or until sauce thickens. Heat refried beans in microwave or small saucepan and stir in remaining 1/4 cup water to thin slightly.
Cut one tortilla in half and fit cut ends at either end of a 9-by-13-inch baking dish. Arrange two tortillas, slightly overlapping, to cover the bottom. Layer 1/3 refried beans, 1/3 meat mixture and 1 can enchilada sauce. Repeat to make a second layer.
Repeat to make a third layer using salsa instead of enchilada sauce. Sprinkle with cheese. Bake for 20 minutes or until lasagna is bubbling and cheese is melted. Let stand 5 minutes before cutting.
If desired, top servings with sour cream and diced green onion.