Chop the onion, garlic and celery.
Heat 2 Tbsp olive oil in a large frying pan and gently sauté the vegetables for 5 minutes.
Meanwhile chop the carrot and pepper into small, bite-sized chunks. Add these to the onion, stir and cook for another 5 minutes.
Chop the tomatoes and add these to the pan. Season with salt and pepper and add the spices. Put the lid on and cook for 10 minutes until the tomatoes have realised their juices.
Drain the lentils and add to the pan. Warm through, then add the kale/spinach and stir. Put the lid on and cook for a further 5 minutes.
Taste, adjust the seasoning and add the parsley and drizzle with freshly squeezed lemon juice or cider vinegar.
Serve warm.