2/3 lb. lamb pieces, trimmed
2 oz. yoghurt (I had some nice sheeps-milk yoghurt, but any, preferably greek or other low-water-content yoghurt, will work*)
1 1/2 medium or 1 large clove garlic, chopped fine
1 T smoked paprika
1/4 t cardamom
1/2 t corriander
1/2 t onion powder
1/2 t garlic powder
1 t oregano
1 t salt
1/2 t pepper
pinch cayenne

(*tip: the second time I made this, my yoghurt was much wetter and gave me some problems sticking to the meat -- this can be remedied by lining a strainer with cheesecloth and letting the yoghurt drain overnight)

Marinate the lamb in the yoghurt-spice mix for up to 4 hours at room temperature, or overnight in the fridge.

Sauce (tzaziki-style):
2 oz yoghurt (same wateryness concerns apply)
1/2 cucumber
1/2 clove garlic, minced
(handful mint, chopped fine)
(handful cilantro, chopped fine)
1 t oregano, crumbled
1 t lemon juice
1/2 t salt
(chopped hot pepper or red pepper flakes)

Half-peel the cucumber, leaving strips of skin (this reduces the toughness and potential bitterness, while leaving the nice green color and some extra flavor). Halve the cuke and scoop out the seeds. Slice into thin half-moons, toss with salt, and put the pieces in a strainer over a bowl. This will draw out excess moisture. Let rest for at least 10 minutes, then squeeze out any additional water before adding the cucumber pieces to the sauce.

Mix cucumbers, garlic, yohgurt, herbs, and lemon juice.

Cooking:
Begin heating the dutch oven, with the lid on, over medium-high heat.

Skewer the lamb on metal skewers, making sure to weight them as evenly as possible (so you will be able to turn them). Fold any long pieces over, skewering them twice, so no pieces hang too far down.

Remove the lid from the dutch oven and place the skewers at an angle down into the pot. Replace the lid.

Cook for 10 minutes, rotate the skewers, and cook another 5-10 min. The pot may smoke somewhat as the drippings burn -- this is OK.

Check the lamb to make sure it is cooked all the way through.

Accoutrements:
2 pocketless pitas, sauteed in butter
tomato
onion
hot peppers
mild peppers
lettuce

the only thing I might do differently next time is to cover the pot less tightly -- as the juices dripped down, they made steam which somewhat impaired the dry-heat effect which defines the tandoor