I had seen these for sale in various Chinese supermarkets, but didn't know what they were. I thought that they might be a herb or spice of some kind, something to add to an Asian Spice Paste. Now I found out, and you might guess that the answer came from my beautiful Thai Bride, that they are Thai pea-sized eggplants, similar to the more well-known and easier to find Thai eggplants, and native to South-East Asia. Normally bitter eaten raw, I think most eggplants have that nature, better when cooked, they pair well with, and enhance curries, cooling spicy dishes. Why did I find out now what they were? I came across several more authentic South-East Asian recipes, some Thai ones, in fact, that have this as an ingredient, and I wanted to try them out. The recipes are for pork or roast duck, not for chicken, and it will work to substitute beef. They can also be added to chili or shrimp pastes.
And now that I have tried them, I found them to be a little bitter, and similar to eating a tomato, when you crunch down on one, the seeds and juice burst out on to your tongue, filling it with its interesting and slightly bitter flavour.