Chicken tikka masala is supposedly Britain's favourite dish. If it's yours, then you may be disappointed, this dish is not it.
Tikka simply means piece, or chunk - so this is chicken pieces, marinated then grilled. The marinade is based on sweet vinegar, not yoghurt - and there's not a drop of food colouring in sight.
It makes a nice starter, or delicious lunch in a chapati roll (page 281 of their cookbook).