Preheat oven to 350 degrees. Pat the salmon dry and cut it into portions if needed to get them to fit easily on ½ of a sheet of parchment paper. Rub some olive oil over one side of the parchment paper and place salmon on one half of the sheet. Pour the salt, pepper, and garlic over the salmon and pat it down.
Place the dill, then lemon slices, then lemongrass over the salmon and drizzle over a bit more olive oil. Fold the parchment paper over the salmon and seal it by making a semicircle of mini creased folds. Fold the last crease under the salmon. Bake in the oven for 25 minutes, take it out, and let rest for 5 minutes before unfolding it and serving.