Mamey sapote by John Spottiswood.

These are about the size of a large sweet potato. The flesh is salmon-colored, with a sweet, berry-like flavor. They're great for eating out of hand, or for making fruit salads or smoothies. Markets often sell them while they're still hard and underripe, so you need to set them on the counter for a few days until they yield when gently squeezed. Peel them and remove the seeds before serving. Substitutes: white sapote OR black sapote