For the lemon yogurt sauce: Add the yogurt, lemon juice, dill, coriander and some salt and pepper to a bowl. Mix together, then drizzle some olive oil on top and garnish with a sprig of dill.
For the collards: Bring a large pot of water to a boil and have a bowl of ice water ready. Boil the collard leaves until bright green and pliable, about 1 1/3 minutes. Transfer to the ice water to cool. Gently squeeze the leaves dry.
Lay out the leaves one at a time on a paper towel to blot, and use a sharp knife to cut out the thick center stems, cutting about three-quarters of the way to the top and making sure to leave 2 to 3 inches uncut at the top. Set the trimmed leaves aside.
Heat 2 tablespoons of the oil in a medium skillet over medium heat. Add the onions and garlic and cook, stirring occasionally, until softened, about 6 minutes. Add the rice, raisins and allspice and cook, stirring, until the rice is well coated, about 1 minute. Add 3/4 teaspoon salt and a few grinds of pepper and remove from the heat. Stir in the dill, parsley, mint and lemon zest.
Lay out one collard leaf with the intact end pointing towards you and the trimmed stem end pointing away. Spoon 2 level tablespoons of the rice filling in the center of the side facing you. Fold the sides of the leaf over the filling, then roll the leaf up tightly away from you like a burrito, starting from the bottom and finishing seam-side down. Repeat with the remaining leaves and rice filling. (Some of the larger leaves may need to be trimmed slightly if they appear too bulky when rolled up.)
Add a splash of the remaining 3 tablespoons oil to a medium saucepan. Arrange the collard rolls in a single layer on the bottom of the pan. Top with enough water to just cover the rolls, then drizzle in the remaining olive oil and the lemon juice. Cover the rolls directly with a round of parchment paper. Bring the liquid to a boil over medium-high heat, then reduce to a low simmer and cook, covered with a lid, for 1 hour. Remove the rolls from the liquid, drain on a paper towel-lined plate and let cool to room temperature. Serve with lemon wedges and the lemon yogurt sauce.