Preheat the oven to temperature 180 degrees C.
Firstly, prepare the Rogan Josh Curry Paste. The best is to do it in a pestle and mortar, but also possible in a small blender/ food processor. You can find this pestle and mortar below with a Free Prime One-Day delivery on Amazon, as well as others to chose from.
Place all Rogan Josh Curry Paste ingredients in a pestle and mortar and grind them into a paste.
Put a large deep non stick pan on a high temperature on the hob. Dice the lamb meat and place it in the pan. Keep mixing it so it starts browning evenly.
Finely chop the green part of the leek, dice the aubergine (with the skin) and throw in the pan, too. Season well with salt and pepper, and the Rogan Josh paste and a 1 tablespoon of red wine vinegar and mix well.
Put all the curry in an oven safe deep dish or a tray. Roast for 1 hour or until the meat os soft. Remember to mix it from time to time, to make sure that everything cooks evenly. You can also add a splash of water if the curry become too thick.
Remove it from the oven and taste. If necessary, adjust the seasoning. Mix some of the lactose free yogurt on top and sprinkle with few leaves of fresh coriander. Serve with basmati rice, either white or brown.