I recently found some beautiful pink-skinned guava in a local wet market. There are several varieties of this seasonal fruit - some you can smell blocks away, others are not as pungent. Whichever variety you buy, they should be fully ripe if you're eating them raw (in cooking, it doesn't matter if they're slightly underripe). To pick ripe guava, press gently - the flesh should 'give' a little. If they're not ripe, keep them at room temperature for two or three days.
Many fruit juice shops are taking advantage of the guava season (and low prices - I bought a kilo for $15) and using them in fruit drinks. Guava juice is very refreshing, despite its grainy texture.
This fruit is delicious as an exotic marmalade. Wash the fruit and chop into chunks. Put into a heavy pan with two cups of water for each kilo of fruit. Boil until the fruit is very soft, then sieve out the seeds. Measure out the soft pulp - for each cup, add an equal measure of castor sugar. Squeeze in some fresh lemon juice and cook until the sugar dissolves. Continue to simmer, stirring frequently, until the mixture starts to thicken. Start testing for the right consistency. Put a blob of the mixture on to a chilled plate - if it's jam-like and not runny when cool, it's ready. Remove the pan from the heat and pour the jam into sterilised, heat-proof jars. Store in the fridge.