Rinse guavas with water. Slice off the top stems and bottom nubs. Cut into 4-6 pieces. The smaller the pieces, the faster it will cook.
Place cut guavas in a large pot and cover with about 4 cups of water. Boil for 20-30 minutes or until softened.
Place a sieve over a large bowl and pour in the guava puree. Using a large metal spoon, push the puree through the sieve, retaining all the seeds. Discard the seeds.
Measure the amount of puree you have. For this recipe, I use a 2:1 ratio of guava puree to sugar. (2 cups guava puree, 1 cup sugar).
Add puree to a large pot and place over high heat. Add sugar and mix until well combined.
Continue stirring until puree has thickened. If you enjoy guava sauce, remove from heat while it's still a bit runny. If you prefer jam, allow puree to thicken more.
Remove from heat and place in glass jars. Cool to room temperature and place in the refrigerator.
Store guava jam in the refrigerator for up to 10 days. ¡Buen provecho!