Preheat the oven to 350°F (175°C).
Bring a large pot of water to a boil. Core the cabbage and carefully separate the leaves. Blanch the cabbage leaves in boiling water for 2 to 3 minutes until pliable. Drain and set aside to cool.
In a large bowl, combine ground beef, cooked rice, chopped onion, minced garlic, egg, salt, black pepper, dried parsley, and dried thyme. Mix well until all ingredients are evenly incorporated.
Carefully trim the thick vein from the bottom of each cabbage leaf to make rolling easier.
Place about 1/4 cup of the meat mixture in the center of each cabbage leaf. Fold the sides over the filling and roll tightly from the stem end to enclose the filling completely. Repeat with remaining leaves and filling.
In a large skillet, heat vegetable oil over medium heat. Add the cabbage rolls seam side down and cook for 2 to 3 minutes until lightly browned. Turn and brown the other side for 2 minutes. Remove from heat.
In a mixing bowl, combine tomato sauce, beef broth, brown sugar, and lemon juice. Stir well.
Place the browned cabbage rolls seam side down in a single layer in a 9×13 inch baking dish. Pour the tomato sauce mixture evenly over the rolls.
Cover the dish tightly with aluminum foil and bake in the preheated oven for 1 hour.
Remove the foil and bake for an additional 15 minutes uncovered to allow the sauce to thicken slightly.
Remove from the oven and let the cabbage rolls rest for 10 minutes before serving.