Add the ingredients to a small bowl or food processor and whisk or blend rapidly to combine them evenly. Using a food processor or blender can make it easier to stir in the oil later, but the dressing can be prepared easily by hand. Pour the oil into the dressing in a slow, steady stream, whisking or blending it as you make the addition. Continue until all the oil has been added.  If using a food processor or blender, add the oil through the hole in the lid as the machine blends the ingredients together. If mixing by hand, place a towel underneath the bowl to prevent it from sliding around as you whisk the ingredients together. You can use the dressing immediately, but if you made it ahead of time, place the poppy seed salad dressing in an airtight container and store it in the refrigerator until ready to serve. Store the dressing inside the refrigerator when not in use. It should stay fresh for a few days to a week.

TL;DR in Indonesian:
Campur cuka, jus lemon, madu, garam dan merica. Sedikit demi sedikit masukkan minyak. Biarkan dingin hingga siap digunakan.