Obtain a Splash Potion of Weakness
Use the Splash Potion of Weakness on the zombie villager
Ensure the zombie villager is not burning (keep it out of sunlight)
Feed the zombie villager a golden apple
Wait for the transformation to complete
Confirm the result by checking for a cured villager appearance
Protect the villager during curing (avoid combat and hazards)
If it fails, repeat with a new Splash Potion of Weakness and a golden apple