Spray a microwave-proof casserole dish with the cooking spray.
Cook the rice in accordance with the directions on the package.
Place the beef and onion in a nonstick pan and sauté for 5 minutes over high heat. Break up the large pieces of beef with a wooden spoon. Drain off the fat. Add the rice and raisins.
Put the cabbage and 3 tablespoons of water in a different microwave-proof casserole dish. Cook for 2 minutes on a high setting. Stir around and cook for 2 minutes on a high setting. Drain, but keep the liquid.
Combine the liquid, tomato sauce, vinegar, Splenda, and pepper in a bowl. Add to the meat mixture.
Spread the cabbage on the bottom of the primed casserole dish. Spoon the meat on top. Microwave, covered, for about 4 minutes on a medium high setting. Turn the dish and microwave for 4 minutes.