Combine rinsed lentils, rice, and 2 cups of water (or vegetable broth) in a medium saucepan. Bring to a boil, then cover, reduce heat to low, and simmer for 20 minutes until the liquid is absorbed and grains are tender al dente. Set aside.

Bring a large pot of salted water to a boil. Cut a deep cone shape around the core of the cabbage to loosen the leaves. Submerge the entire head of cabbage into boiling water for 3-5 minutes until leaves soften. Carefully peel off 10–12 large leaves using tongs. Lay flat on towels and pare down the thick central vein on the back of each leaf.

Heat olive oil in a skillet over medium heat. Sauté onion, garlic, and carrot for 5 minutes until soft. Stir in smoked paprika, oregano, cumin, salt, and pepper; cook 1 minute until fragrant. Mix this sautéed vegetables into the cooked lentils and rice along with fresh parsley and mint.

In a bowl, whisk together crushed tomatoes, tomato paste, vegetable broth, and lemon juice. Spread a thin layer of sauce across the bottom of a large deep skillet or baking dish. Place a cabbage leaf flat, spoon 2 to 3 tablespoons of filling near the stem end, fold sides inward, and roll tightly toward the top. Arrange seam-side down in the prepared dish.

Pour the remaining tomato sauce evenly over the cabbage rolls. Cover and simmer on the stovetop over medium-low heat for 40-45 minutes (or bake covered at 375°F / 190°C for 50-60 minutes) until tender. Garnish with fresh chopped parsley before serving.