Peel and cut guavas into small pieces (about 1/2 inch pieces.) Transfer to a pot and add 2 C of water, sugar, vinegar, lime, and salt.
Bring to a boil (on high heat.) Then reduce heat to medium and boil for about 30 minutes.
Remove from stove and set aside to cool for 15 minutes.
Pour the mixture through a metal sifter (into a pan)to separate out the seeds. Use a spoon to force the mixture through the sifter. Pass the mixture through the sifter for a second time.
Transfer the guava mixture back into the pot. Add the remaining 1 C of water on medium high until just at a boil. Reduce heat to medium-low and simmer for about 30 minutes or until thickened.
Move pot from stove and set aside to cool. Transfer jam into jars and refrigerate. Jam will stiffen as it cools.
This recipe makes about 12 ounces. Of course you can increase the amount if you need to.