1. Place all ingredients in a large heavy saucepan.
2. Bring to the boil, stirring gently until brown sugar has completely dissolved.
3. Reduce heat and simmer for 30 to 45 minutes, stirring regularly until a thick syrup consistency is reached.
4. Serve immediately or pour mixture into clean jars and seal well to store in a cool, dark place.
Feijoa, also known as 'pineapple guava' grow in South America, but they are also familiar to folks in California. You might even have a hedge around your house that is actually a feijoa bush. The fruit is only ripe in California during the month of November and only after it falls off the bush, so if you have one, watch it closely and spread a tarp under the bush to catch the fruit.
If you don't have a feijoa bush in your neighborhood, check your larger grocery stores. These fruit are shipped when they are in season in South America and are available at times here. They are well worth the effort if you find them. Feijoa (pineapple guava) has a tart flavor, similar to lemon, but with a creamy texture. If you find them, give them a try!