I grew this squash last year and will grow even more this year. I'm not sure what size you guys are tasting. They need to be smaller than an actual avocado, I pick them when I can wrap my thumb and index finger around them and they touch or are close to touching. If you get them much bigger, they DO tend to get fibrous and seedy.
When picked at the right size, they do have a buttery texture and taste.
Also, they don't hold up long if not refrigerated, they'll stay fresh about a week in the fridge, maybe two days at room temp. I 'm not a chef, but I just lightly saute them with a little butter and garlic. I like it much better than most other summer squash.
Oddly enough, if you let these little fellows grow out at the end of the season they grow to pumpkin size and turn burnt orange. A chef in my town makes soup out of these larger kind. Hope this helps.
I don't know if they're the specific variety Yuno's grows, but yes, Han Ah Rheum had some somewhat anemic looking ball suash tonight - probably do better at one of the bigger stores than the one on 32d St. but the ones I got are OK. Haven't tried 'em yet, but when I saw them so soon after I'd googled them, I of course couldn't walk out without them.
I don't now for sure, but it appears more commonly to go under the more prosaic name "Korean ball squash." It sounds and looks like it probably tastes like zucchini - I suspect the "buttery richness" aspect is more in the tastebuds of the beholder than otherwise.
Here's the page on a seed seller's site that has a picture: www.evergreenseeds.com/orsquaskorgr.html Unless it's "obscure" even in Korean cuisine, Han Ah Rheum might be a place to check - the one on 32d St doesn't have much or great produce, but they do tend to have "typically" Asian/Korean things. They've always had the now-trendy shishito peppers, for example, and those little yellow and white Korean melons when they're in season...
I've tried it, and I did buy it at the Greenmarket,
from Yuno's. I'm not a big fan. I sliced and sauteed it,
and perhaps I should have done more, but it has a lot of seeds.
(I like to julienne regular zucchini lengthwise, so it is
in strands, and avoid all the seeds, and sautee it with olive oil, garlic, salt, pepper and herbs.) A friend of mine said
he sliced an avocado squash into eggs with shallots and he
liked it, but.... I found the texture kinda dry.