The century egg, also known as preserved egg, thousand-year egg, thousand-year-old egg, (Chinese: 皮蛋; pinyin: Pídàn; literally "skin/leather egg" or Chinese: 松花蛋; pinyin: sōnghūadàn; literally "pine-patterned egg") ; (ไข่เยี่ยวม้า khai-yiew-ma (in Thai)) is a Chinese delicacy made by preserving duck, chicken or quail eggs in a mixture of clay, ash, salt, lime, and rice straw for several weeks to several months, depending on the method of processing. The yolk of the egg is concentrically variegated in pale and dark green colors while the egg white is dark brown and transparent, like cola.The yolk is creamy with a strong aroma and an almost cheese-like flavor. The egg white has a gelatinous texture similar to cooked egg white, however with very little taste. Some eggs have patterns near the surface of the egg white likened to pine branches.

1. Preparing the pickling solution:

• Water 1L
• Sodium chloride(NaCl) 72g
• Sodium hydroxide(NaOH) 42g

Dissolve the NaCl and NaOH completely in water. Bring the solution to a boil and allow it to cool down before use.

2. Submerge the eggs in the saline solution, and store at 15 to 20oC for about 10 days.

3. Pick out the pickled eggs and rinse them. Then allow them to dry naturally.

4. Coat with PVA (polyvinyl acetate) or some other non-ventilated packaging material. An alternative is to add red soil to the saline solution after the pickled eggs are removed. Coat the eggs with the mud, and roll them in rice husk. Age for about 2 weeks.

5. Crack the eggs lightly and remove the shell. The white of the egg will have a grayish, translucent color, and a gelatinous texture. The yolk, when sliced, will be a grayish-green color.

6. To serve, cut into wedges and serve with bean curd (tofu) as an appetizer, or as a condiment for dishes such as rice gruel (congee).

Source: http://www.agnet.org; Wikipedia