A couple of people have asked for a scaled down quantity version of jb's recipe and since I always keep notes on the recipes I cook, I thought I would share the below which is my interpretation of the jb method and which I've cooked quite a few times now with good success. These potatoes come out fully cooked but in no way mushy and seem to tolerate further cooking when added to the final dish. Even tossing them around when cooking a Bombay aloo they keep their shape in a way that boiled potatoes would not, so I'm convinced this oven bake method must be how the BIRs do it.
No problem to cook these, freeze then defrost and use in a curry, but the qty below will stretch to 3-4 curries, so isn't a huge amount. It's actually a super easy and low-stress cook with nothing difficult at all!
1 chefs spoon or 3 level tablespoon veg oil
1 heaped teaspoon G&G
Half teaspoon cumin seeds or panch phoran - *jb specified cumin, I prefer panch phoran, but either will work
Half teaspoon cumin powder
Half teaspoon turmeric powder
1/2 level teaspoon salt
2 heaped dessertspoon chopped tomatoes
750g potatoes peeled and cut into large chunks
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Heat oil and fry G&G with panch phoran seeds. Add turmeric and cumin powder with tomatoes and fry. Add potatoes and fry for 3-5 mins, stirring a little.
Place in lidded oven proof dish, cover pan and place into preheated oven fan 130C for 60 mins. This works for large potato chunks, if you cut yours smaller then maybe a shorter cook will be enough. Obviously the size, shape and material of the dish has an influence too. A thin later of potatoes spread across the bottom of a big metal dish will cook much quicker than a piled high heap of pots in a small Pyrex dish.