Instructions:
- Preheat oven to 375°F (190°C). Slice the tops off the peppers. Carefully scoop out the seeds and white membranes. Set peppers aside.
- Cook the rice according to package directions until done. Set aside to cool slightly.
- In the large baking dish, combine the crushed tomatoes, water/broth, dried oregano, salt, and pepper. Stir well to combine, forming the baking sauce base.
- Heat olive oil in the large skillet over medium heat. Sauté the chopped onion until softened (about 5 minutes). Add garlic and cook for 1 minute more until fragrant.
- Add the ground beef to the skillet. Break it up and cook until fully browned. Drain off any excess fat.
- Stir in the drained diced tomatoes, tomato paste, thyme, Worcestershire sauce (if using), salt, and pepper into the skillet mixture. Cook for 2 minutes until the tomato paste darkens slightly.
- Transfer the meat mixture to the large mixing bowl. Add the pre-cooked rice and the fresh parsley. Mix thoroughly until everything is evenly incorporated. Taste and adjust seasoning.
- Gently spoon the filling mixture into the hollowed-out peppers, packing firmly but not compressing too tightly.
- Place the stuffed peppers upright into the prepared tomato sauce in the baking dish. They should nestle snugly.
- Cover the baking dish tightly with aluminum foil. Bake for 35 minutes.
- Remove the foil and continue baking for another 15–20 minutes, or until the peppers are fork-tender and the internal temperature reaches 165°F (74°C).
- Let the peppers rest for 5-10 minutes before serving, spooning extra tomato sauce from the bottom of the dish over the top.