Gac fruit (Momordica cochinchinensis) is a Southeast Asian fruit found throughout the region from Southern China to Northeastern Australia, mostly Vietnam. The meat inside is bright red and soft with flat, round, hard, brow/black seed. The meat is smashed and mixed with sweet rice then steamed to make a delicious dish.
The longan literally means "dragon's eye" in Chinese. In taste, it is similar to a lychee, but it is a bit smaller and is often eaten in bunches as a dessert (fresh fruit is often used for a dessert course in Chinese cuisine).