1. Chop the onions, eggplant, garlic, ginger and coriander. Set aside in a bowl.
2. Cut the lamb into small pieces.
3. Heat the oil in a frypan. Seal the lamb for about a minute on each side. Remove from the heat.
4. Place all of the meat, vegetables, herbs and spices and into the slow cooker.
5. Pour in the diced tomatoes and water. Add the rogan josh paste into the slow cooker and stir until well combined and all clumps of paste are gone.
6. Add the coconut cream and stir through.
7. Allow to cook slowly on low heat for a minimum of 5 hours.
8. For the last hour of cooking, turn slow cooker heat to high.
9. Serve with basmati rice. Garnish with coriander.