It's
guanabana, for future searches. The fruit is popular in Caribbean countries and South America, but you are probably most likely to find it in SE Asian groceries. It's a common enough smoothie flavor at Viet places. You might stop by the stores on Argyle where I have seen it off and on. My favorite fruit, mostly because I grew up with it in FL. I hadn't read about its supposed cancer-fighting powers until the last few days. I assume its the next super fruit and in high demand.