Many fruits are called “plum” here. Mango is sometimes called plum. There’s something called a sour plum that’s kumquat-sized but not citrus. Then there’s this:
Golden plum, or, if you’re from Trinidad and Tobago, pomcitty, also spelled (properly, I guess) pomme cythere. These are a little passed the point where I usually like to buy them, but show the golden color. I prefer them before they start to turn golden because they’re easier to eat. If you let them get to this point, the fibers on the seed become more pronounced, and it’s hard to get the flesh off. Let me show you:
If you buy the golden plum before it gets golden, the seed isn’t as developed and you can pry the fruit off more easily. Here’s the beast, liberated:
When they hit this point, they get pretty sour. A good sour, with hints of sweet, but sour. Think under-ripe prune plum sour. Sour candy sour. There’s a very slight, almost grassy aroma to it, which is interesting. When they’re more green the sour isn’t as pronounced, and the flavor is much more mild.
They work well in fruit salads as a counterpoint to other mild, sweet fruits, like bananas and rambutan. Peeled and stewed, it makes a nice chutney, and you don’t need to wrestle with the seed; just fish it out of the chutney once it’s done cooking. Use a recipe for mango chutney and dial back the vinegar or other acid to compensate.