To get ghast tears, you will have to defeat regular ghasts that spawn in the Nether (more commonly in the Soul Sand Valley). As for the second ingredient, you can head to the same biome and shovel ...

How To Craft Dried Ghast Blocks Dried Ghast blocks are relatively simple to craft; but what's not so simple is getting one of the two ingredients needed to make them. Soul Sand is going to be ...

These can be tricky to obtain since ghasts fly over lava lakes, and their drops can fall into the hot liquid after death. For each Potion of Regeneration, a ghast tear is required.