I've never cooked with guava before, at least not until yesterday. Certainly I've seen it in the "exotic" section of the supermarket, but it wasn't until I went to Southern California that I witnessed the fruit in such bulk, piled high in produce bins of San Diego and Los Angeles, spilling from boxes at the farmer's market in Ojai.
At each locale, their balm was incense-thick, musky, and sweet as syrup; driving home to Greenville with three pounds of ripe guava in the back seat is a lovely experience!
Unfortunately, those hefty three pounds yielded a puny eight ounces of jelly- but whatta jelly! Prepare some yourself, and you, too, can enjoy it for breakfast with cream cheese and toast. Spread it on pound cake. Fill a cookie. Glaze a cheesecake. Crown a custard. Flavor a buttercream. Top a cracker. Brush on pork chops. Nibble with manchego. Drizzle on shortbread. Sandwich with cheddar. Eat straight from the jar!
Wash the fruit, remove stem ends, slice thin, and toss into a large, non-reactive pot. Fill with water just to cover. Bring to a boil, lower heat, and simmer until the guava is very soft (30-40 minutes).
Pour entire contents of pot into a jelly bag set over a bowl. Let sit overnight.
Discard the cooked fruit and measure the amount of juice it has produced. Pour into a heavy, non-reactive pot.
For each cup of liquid, measure out 1/2 c sugar and 1 tsp lime juice. Add to pot and bring to a boil. Lower heat to medium and simmer, stirring often and skimming off any scum that forms on the surface. Cook for about 20 minutes, until it reaches 220 degrees (high altitude jammers: drop 2 degrees for each 1,000 feet above sea level) or sets up on a frozen plate.
Refrigerate, or can according to manufacturer's instructions.