Guava juice is very common in the Caribbean Islands. It seems each island has its own variation on this tropical drink. There's a variation of guava juice made in Jamaica (see link below), but this is how I learned to make guava juice in the Cayman Islands.
Things you'll need:
1. Thinly slice about 20 ripe guavas. You don't need to peel them, but the skin is slightly bitter, and you may not want the bitterness in your juice.
2. Add the sliced guavas to a large pot with 3 cups of boiling water.
3. Boil the guavas for about 10 minutes or until soft.
4. Crush the guavas with a potato masher.
5. Strain the guavas to obtain the juice. The strainer you see pictured will allow some pulp in the juice. If you don't want any pulp use a strainer to make jelly.
6. Squeeze about 10 limes to get about half a cup of lime juice. It's also OK to substitute lemons at this step. You just need a fruit that is a little tart to counteract the guava.
7. Strain the lime juice and add to the guava juice.
8. Add half a cup of orange juice for sweetness. You can actually add any type of juice you like. Typically pineapple juice is used here.
9. This recipe makes about 5 cups of guava juice.
10. You may add sugar if you want the juice to be sweeter and you may add water if the juice is too thick for you.