Dry-grind the indicated ingredients except for the chicken, cream, egg and, of course, the food colour. One may dispense with the ginger if need be, but the garlic cannot be escaped.
Give the ingredients a single spurt in a mixer to make a "coarse paste" (see note). Remove in a bowl to which the chicken cubes may be added. In my experience, coarse mixtures help retain good taste and flavour.
Drop in the beaten egg, followed by a pinch of food colour. Then gently massage the marinade into the chicken.
Heat a small amount of oil in a cooking pot, add the marinated chicken and stir-cook till done. Use the toothpick test to check if fully cooked.
Skewer the chicken pieces, drizzle some oil over the skewered botis and roast directly over a gas flame till darkish spots appear.