Preheat oven to 375°F (190°C). Remove core from Napa cabbage and carefully separate 12-15 large outer leaves. Place leaves in a large microwave-safe dish with 2 tablespoons water. Cover and microwave on high for 3-4 minutes until wilted and pliable. Alternatively, steam over simmering water for 5 minutes. Let cool slightly, then trim thick stem portion flush with leaf for easier rolling.

In a large bowl, combine ground turkey, cooked rice, diced onion, minced garlic, fresh dill, parsley, beaten egg, salt, and pepper. Mix gently with your hands until just combined. Avoid overmixing to keep filling tender. Let mixture rest for 10 minutes to allow flavors to meld.

Place about ⅓ cup of filling near the stem end of a prepared cabbage leaf. Fold stem end over filling, fold in sides, and roll tightly but gently toward the tip. Place seam-side down in a 9x13-inch baking dish. Repeat with remaining leaves and filling.

In a medium bowl, whisk together crushed tomatoes, stock, brown sugar, smoked paprika, and additional salt and pepper to taste. Pour sauce over and around cabbage rolls, ensuring they are mostly submerged.

Cover baking dish with lid or aluminum foil. Bake for 45 minutes. Remove cover and bake for an additional 15 minutes, until sauce has thickened slightly and rolls are tender. Let rest 10 minutes before serving. Garnish with fresh herbs and a dollop of sour cream if desired.