This is the egg yolk fruit

The egg yolk fruit is also known as the fairy peach, so named because the flesh resembles a cooked egg yolk. Its peel is smooth and the exocarp is extremely thin and difficult to separate from the pulp. The mesocarp is fleshy, plump, soft, egg-yellow, has low water content, and tastes sweet, like a cooked egg yolk. Seeds are usually 1 to 2, nearly round or oval. The fruit matures in December and takes 4 to 7 days after harvesting before it can be eaten.