I hesitate to criticise, but this seems like a strange recipe. First the lamp is "seared" for 30 mins on a low flame (not much chance of 3 kg of lamb in a pot on a low flame searing at all), then raw G&G and spices are added and a few mins later the whole thing is covered in water for a good long stew.
Seems like a great way to get raw garlic, ginger and spice flavours coated onto the outside of stewed meat.
What's wrong with the way I've seen every other BIR do it, which is to cook the G&G, spices and tomato first, then add the meat and have those BIR flavours soak into the meat as it cooks? You'll never get the right flavours (IMHO) by adding the holy trinity (G&G, spices, tomatoes) to a big pot of cooked meat, as you won't be frying at that stage, but rather boiling.