Remove the core from the cabbage head, then gently boil the whole head in a large pot of salted water for about 5 minutes. Once softened, carefully remove the outer leaves and set them aside.

In a large skillet, sauté the chopped onion and minced garlic over medium heat until translucent, about 3-4 minutes. Add in the ground beef and cook until browned, seasoning with salt, pepper, and thyme. Drain excess fat if necessary.

In a large bowl, mix the cooked rice into the meat mixture, then stir in the tomato sauce, diced tomatoes, and soy sauce until well combined.

Preheat your oven to 350°F (175°C). In a 13x9-inch baking dish, layer the bottom with some cabbage leaves, followed by the meat mixture. Continue layering until all ingredients are used, finishing with a layer of cabbage on top.

Cover the dish with foil and bake in the preheated oven for 30 minutes. If using cheese, remove the foil during the last 10 minutes and sprinkle it over the top to melt.

Once bubbling and golden, remove from the oven, allow to cool slightly, and serve warm.