If using dried chestnuts, soak in warm water 8 hours.
To remove shell and skin from fresh chestnuts, use a sharp paring knife to score an X on each side of the chestnut shell.
Drop scored chestnuts in a small saucepan of boiling water and boil 2 minutes to soften shell.
Drain and cool slightly.
While chestnuts are still warm, peel off hard shell and furry inner skin.
Use a cleaver to chop chicken into 2-inch square pieces.
Pat chicken dry with a paper towel.
Heat 5 cups oil in a wok over high heat to 350°F (175°C).
Reduce heat to medium.
Carefully lower chicken pieces into hot oil with a slotted metal spoon.
Deep-fry half the chicken pieces 2 minutes or until golden.
Remove chicken with slotted spoon, draining well over wok; set aside.
Repeat with remaining chicken pieces.
Remove oil from wok.
Place fried chicken and chestnuts in a medium saucepan.
Add wine, soy sauce, sugar, ginger root, green onions and water; stir to mix.
Bring to a boil over high heat.
Reduce heat to low and cook 30 to 40 minutes until only 1/3 cup of liquid remains.
Remove green onions and ginger root.
Dissolve cornstarch in water to make a paste.
Add to saucepan and stir until sauce thickens slightly.
Stir in 1 tablespoon oil.
Serve chicken and sauce on a small platter garnished with lettuce.