It sounds vaguely like a Spanglish cussword, but it's Averrhoa carambola, a.k.a. starfruit. The seedling I planted in my backyard years ago is now probably over 25 feet tall and veerrry productive. Why, I'd wager its annual yield exceeds the Gross National Product of some small countries! But the fruit is so sour as to be inedible. I know, I've tried. Last year, muttering the family motto "waste not want not" under my breath all the while, I marched out there and picked a dozen of the fattest, ripest fruits. I ran them through a juicer and kept adding sugar, an obscene amount, until I could force a glassful of the green-gold liquid past my lips. It made my molars itch, and the back of my throat felt as if it had just been massaged with a wood rasp. I told myself that a draught so -- uhmm -- bracing, must be very good for me! Over the course of the next 24 hours my digestive tract did all it could to dissuade me of that theory.
There are a couple of things I've learned in the meantime. First, fruit trees grown from seed, as this one was, might hearken back to some far less civilized ancestor and not produce usable fruit. Second, the acrid aftertaste I attributed to an overabundance of citric acid (Vitamin C, as in, protects you from colds) was more than likely supplemented with a strong dose of oxalic acid (as in, shreds your kidneys!) Normally there's not enough to hurt a healthy person, but most likely the process of juicing concentrated what was already, due to the poor genetics of the tree, an overly large amount.
This year my wicked carambola tree is flaunting another huge crop. I look at the heavy clusters of beautiful fruit with disdain. I'm married to a man with a chainsaw -- I could easily have it whacked!! But it is just so pretty. That should count for something, shouldn't it?