Wash and scrub the outside of the pineapple well.
Remove the crown of the pineapple and discard.
Cut the pineapple fruit into chunks and set aside.
Remove the peeling and hard inner core from the pineapple. Do not discard. Cut into chunks.
Peel and grate ginger.
Place pineapple peeling and core chunks and ginger into a pot with 2½ cups water. Let the pot come to a boil, then reduce the heat and simmer for about 20 minutes.
After the cooked pineapple has cooled, pour the water into a blender. Discard the cooked chunks.
Add the reserved pineapple chunks and blend well.
Pour the blended mixture through a sieve. I let it drain for about 5 minutes into a large bowl and then funneled into a mason jar.
Add the juice of one lemon.
Stir and enjoy!
This juice refrigerates well for about a week.