Fill a large saucepan with water, bring to a boil, then carefully core the cabbage and submerge it in the boiling water. Let it sit for about 3-4 minutes until the outer leaves soften and become pliable. Carefully peel off about 8-10 large outer leaves, trimming the thick vein at their bases with a knife or scissors.
While the cabbage is boiling, sauté the chopped mushrooms and minced garlic in a skillet over medium heat until fragrant and slightly browned, about 5 minutes. This adds a smoky umami flavor that will deepen the filling.
In a mixing bowl, combine the cooked lentils, sautéed mushrooms, chopped dill, dried thyme, a splash of vinegar, and a pinch of salt and pepper. Mix until the filling is moist but cohesive. Adjust seasoning as needed.
Lay a cabbage leaf flat on your work surface. Spoon about 2-3 tablespoons of the filling near the base of the leaf. Fold in the sides and roll tightly from the bottom, like a burrito, sealing the filling inside. Repeat with remaining leaves and filling.
In a deep skillet or saucepan, heat the tomato sauce with smoked paprika until gently bubbling, about 3-5 minutes. Carefully nestle the cabbage rolls seam-side down into the sauce, ensuring they are partially submerged.
Cover the skillet and simmer gently over low heat for about 30-40 minutes, until the leaves are tender and the filling is heated through. The sauce should be bubbling softly and thickened slightly.
Once cooked, carefully transfer the cabbage rolls to a serving dish, spooning extra sauce over the top. Let them rest for 5 minutes to allow flavors to meld.
Garnish with additional fresh dill or herbs if desired. Serve warm, enjoying the vibrant flavors and tender, curled cabbage leaves around the hearty filling.
