In a large skillet or pot over medium heat, add the olive oil and diced onions. Cook, stirring now and then, until the onions are soft and translucent, about 8 to 10 minutes.

Add the rice, parsley, mint, dill, salt, allspice, black pepper, sugar, and Aleppo pepper. Stir until everything is well combined and the rice is coated.

Pour in the water and the juice of half a lemon. Reduce the heat to medium low, cover, and simmer until most of the liquid is absorbed, about 12 to 15 minutes. The rice will be partly cooked. Remove from the heat and let the filling cool until it is comfortable to handle.

While the filling cools, drain the grape leaves and rinse them well to wash off the brine. Trim off any thick stems. Set a few torn or imperfect leaves aside to line the pot.

Lay a grape leaf flat with the shiny side down and the veins facing up, stem end toward you. Place about 1 tablespoon of filling near the stem end. Fold the stem end over the filling, fold in both sides, then roll it away from you into a snug little log. Do not roll too tight, since the rice needs room to expand.

Line the bottom of a Dutch oven with the reserved leaves. Arrange the rolls seam side down in tight rows, layering them as needed.

Pour the 1 ½ cups water, 1 teaspoon salt, and the juice of half a lemon evenly over the rolls.

Set a heatproof plate upside down directly on top of the rolls to keep them submerged and stop them from unrolling.

Cover and bake at 350 degrees for 1 hour.

Leave the rolls in the pot for about 20 minutes to cool and set.

Garnish with lemon and a final drizzle of olive oil. Serve at room temperature or chilled.