In a frying pan, heat the oil over medium heat and toast the cumin seeds for a couple of minutes.
Add the onion and cook for a few minutes until translucent and starting to soften.
Add the ginger and garlic and cook for another minute.
Add the spices, stir well and cook for another minute or so.
Add the chopped tomatoes, stir well to ensure the spices don't stick to the base of the pan. Bring to the boil, then reduce to a simmer and cook for five to ten minutes until the sauce has reduced and thickened. By doing this now, your sauce won't become watery in the slow cooker when the red pepper releases moisture as it cooks.
Transfer the sauce to the slow cooker, add the red pepper and chickpeas.
Cook on low for 6-7 hours.
Just before serving, heat a little oil in a pan and fry the paneer cubes for 2-3 minutes, turning, until they are brown on all sides.
Sprinkle the black onion seeds on the chickpea curry, top it with the paneer and serve with rice or naan bread.