Preheat oven to 375 degrees F. Spray 9 x 13″ baking dish with cooking spray and set aside.
Spray a large skillet with cooking spray, and heat over medium high heat. Add turkey to the hot skillet, and sprinkle with chili powder, oregano, cumin, and garlic powder. Brown and crumble meat until mostly cooked through.
Stir in rice, salsa, and water, and bring to a simmer. Reduce heat to medium, and simmer for 5 minutes. Stir in cabbage until well mixed, and turn off heat.
Transfer meat and cabbage mixture to prepared baking dish. Sprinkle one cup of shredded cheese over the top. Arrange sliced tomatoes evenly over the cheese, and sprinkle with green onions. Sprinkle remaining 1/2 cup of cheese over the top. Bake in preheated oven for 20 minutes, then serve.