Preheat the oven to 375°F (190°C). Lightly oil a baking dish and spread a thin layer of tomato sauce across the bottom.

Warm 1 tablespoon of oil in a skillet over medium heat. Add the chopped onion and sauté until soft and translucent, about 5–7 minutes. Add the garlic and cook for 30–60 seconds until fragrant. Remove from heat.

In a large bowl, mix the cooked lentils, cooked rice, the sautéed onion and garlic, diced tomatoes, oregano, cumin, and a generous pinch of salt and pepper. Taste and adjust seasoning.

Bring a wide pot of water to a boil. Submerge the cabbage leaves for 2–4 minutes until flexible and pale green. Drain and pat dry. Trim any thick central rib so the leaves roll easily.

Place about 1/3 to 1/2 cup of the filling near the stem end of each leaf. Fold the sides over the filling and roll tightly toward the tip. Repeat with remaining leaves and filling.

Arrange the rolls seam-side down in the prepared dish. Pour the remaining tomato sauce evenly over the rolls.

Cover the dish tightly with foil and bake for 30 minutes. Remove foil and bake another 10–15 minutes to thicken the sauce and allow edges to brown slightly.

Let rest for 5 minutes, garnish with chopped parsley, and serve warm.