Combine chicken and marinade ingredients in a shallow dish & place in the refrigerator; let marinade for 24 hours.
Preparation of batter:
Place dry ingredients in a small bowl & mix well. Place the ice water and egg in another bowl and slowly add the dry ingredients to the water. Mix lightly but do not over beat. There should be a few small lumps in the batter. Dredge the marinated chicken in some flour, then dip into the tempura.
Deep fry the "dredged" chicken in enough oil to completely sink the breast underneath the surface. The oil must be 350 degrees which is the preferred frying temp of most professional cooks. (Make sure it's not over-used and too dark, or smoking.).
Note: 400 degrees would fry the surface of the breast too dry, and leave the inside underdone.
Fry at this temp for either 15-20 minutes, or until the piece has floated at the surface for a minute. Dark meat takes a few minutes longer -- especially legs.