Carefully remove the core from the bottom of the cabbage head using a sharp knife. Be gentle to keep the leaves intact.

Bring a large pot of salted water to a rolling boil. Carefully place the whole cabbage head into the boiling water, core-side down. Cover and cook for about 10-15 minutes, or until the outer leaves begin to soften and peel off easily.

Using tongs, carefully peel off the softened outer leaves. Return the cabbage head to the hot water and continue to cook and peel off leaves until you have about 12-16 good-sized leaves suitable for rolling. You may need to trim the thickest part of the central rib from each leaf to make them more pliable.

In a large mixing bowl, combine the ground beef, ground pork, soaked and drained rice, finely chopped onion (from filling ingredients), minced garlic (from filling ingredients), egg, chopped parsley, chopped dill (if using), 1.5 tsp salt, and 0.5 tsp black pepper. Mix thoroughly with your hands until well combined.

Lay a cabbage leaf flat on a clean surface. Place about 2-3 tablespoons of the meat filling near the stem end of the leaf. Fold the sides of the leaf over the filling, then roll tightly from the stem end up to create a compact roll. Repeat with the remaining leaves and filling.

In a large Dutch oven or oven-safe pot (that can hold all the rolls snugly), heat olive oil over medium heat. Add the finely chopped onion (from sauce ingredients) and cook until softened, about 5-7 minutes. Add the minced garlic (from sauce ingredients) and cook for another minute until fragrant.

Stir in the crushed tomatoes, beef broth, brown sugar, apple cider vinegar, lemon juice, bay leaf, 0.5 tsp salt, 0.25 tsp black pepper, and optional red pepper flakes. Bring the sauce to a gentle simmer.

Carefully arrange the cabbage rolls in the simmering sauce, packing them tightly in a single layer if possible, or in two layers. If you have any leftover small cabbage pieces or ribs, you can scatter them between the rolls for extra flavor and to prevent sticking.

Ensure the rolls are mostly submerged in the sauce. Add a little more broth or water if needed. Bring the sauce back to a gentle simmer, then reduce heat to low, cover the pot, and cook for at least 1 hour 40 minutes (100 minutes), or up to 2 hours, checking occasionally to ensure the sauce isn't reducing too much and the rolls are tender.

The cabbage rolls are done when the cabbage leaves are very tender and the rice and meat filling are fully cooked. Remove the bay leaf before serving.

Serve hot, garnished with a dollop of sour cream or fresh dill, if desired.