Wash, dry and cut the karela in half. Remove the seeds and then cut the karela into small slices. Rub the pieces in salt and leave overnight in an airtight container (if you are short of time, you could leave them for an hour or so before cooking).
After the karela have sat in the salt overnight, you can start on preparing the keema. Heat the oil and fry the onions until brown.
Add the garlic and ginger and stir through until the raw smell of the garlic and ginger has gone.
Next add the tomatoes and tomato puree and all the spices, except the garam masala and stir through. Add 100 ml of water, let the mixture simmer for 10 minutes with the pan lid on. Keep checking the masala is not sticking to the pan. If it dries out, add a more water.
Whilst the masala base is simmering, start preparing the karela. Wash the salt off the karela and then dry them off.
In a separate pan, heat the oil and add the coriander seeds, sliced onion, chillies, bullet pepper chilli, lemon juice and the karela. Cook together on a medium to low heat for 10 minutes until the karela have softened.
Go back to the masala pan and add the mince meat, break up the mince with the back of your spoon and cook on medium heat until the mince has browned in the masala.
Then add 150 ml of water, cover the keema pan with a lid and turn the heat to low, simmer for 15 minutes.
Next, add the karela to the keema pan and simmer for a further 10 minutes.
Add the garam masala, stir through. Then garnish with fresh coriander and serve with fresh chapatis.