The base of this recipe comes from our forum colleague johnfb (check out his blog for some great Indian recipes!). I have made a few modifications in the recipe and I have his permission to post my slightly modified recipe here. There are thousands of recipes for tandoori and I don't claim this to be an original in any way but this recipe is optimal in my opinion.
Marinade:
For 600-1000 grams of bone- and skinless chicken breast, enough for 2-4 servings, you will need:
100 ml full-fat yoghurt (10% fat)
1 tsp fenugreek leaves
½ tsp salt
Juice of one lemon
1 tbsp kashmiri masala (from the store or recipe below)
2 tbsp tandoori masala (from the store)
3 tbsp curry paste of your preference (from the store)
1 tbsp grated fresh garlic
1 tbsp grated fresh ginger
1 tbsp chili paste (e.g. Sambal Oelek)
2 tsp dried mint
2 tsp Liquid Smoke (if you don't grill on charcoal)
Red caramel colouring
Mix. The colouring adds nothing to the taste, but traditionally, tandoori chicken is heavily coloured red.
Kashmiri Masala:
2 cinnamon pods
2 tbsp black cumin (kala jeera)
1 tsp cardamom seeds
2 tsp black pepper
½ tsp cloves
½ tsp mace
1/8 nutmeg nut
Chili to your liking; a kashmiri masala is not supposed to be hot.
Roast the spices in a dry skillet. Let cool and grind. Keep in a tight jar.
The chicken: Make a few incisions in the breasts. Massage the marinade into the meat and marinate, refrigerated, for one day.
On the second day, make a shakrooti (recipe follows) and some rice, turn on the oven on maximum heat plus grill. If you happen to have a tandoori oven you will use that of course.
Place the chicken on greased aluminium foil (to make the cleaning process easier afterwards) as high up as possible in the oven. Don't leave the kitchen - this is a very quick process! After 3-5 minutes, when black bubbles start to develop on the breasts, turn and continue another 3-5 minutes. The breasts should be ready now. Check with fork and knife. They should be juicy but have no trace of pinkish liquid in them. If they are not ready, turn off the grill and let them bake for a few minutes more. Tandoori chicken should have a very burnt colour, almost black. It's the character of the dish.
Drop some melted butter mixed with chaat masala (recipe follows) over the breasts and serve with rice and a generous amount of Shakrooti salad (recipe follows).
Chaat masala:
1 tbsp cumin
1 tbsp black pepper
5 cloves
1½ tsp dried mint
1/4 tsp dried ajowan seeds
1/4 tsp hing (asafoetida)
1 tsp salt
3 tbsp dried mango powder
1 tsp dried ginger
1 tsp cayenne pepper
1/4 tsp citric or tartaric acid
Roast the dry seeds. Let cool, grind and mix with the rest of the ingredients.
Shakrooti
This salad is not typically Indian. It exists in numerous varieties in Asian countries. My Kyrghyz wife tells me that they have the same there, called shakarat, but it's without cucumber. I don't know if shakrooti is traditional but it goes excellently with tandoori chicken.
3-5 large ripe tomatoes
½ kilo (about) cucumber
1 large onion (or a corresponding amount of fresh onion or scallions)
1 small green chili
1 bunch fresh coriander
Juice of one lemon
Salt, sugar, black pepper.
Chop everything. Mix. Add a little sugar if you like. The amount of chili is to everyone's taste. I prefer this dish mild and make the chicken hot instead, but as said it's a personal matter.
PS Hing or Asafoetida is a very particular spice. The special thing about it is that its scent is easily detected by dogs, even after it has passed the human digestive process. Therefore, it was served on a daily basis in Swedish prisons in the 18Th and 19th centuries. Any fugitives were easily found by dogs.