Begin with draining the yellow split peas and place in a pan with plenty of cold water, bring to a boil and then simmer for 25-30 minutes or until semi-soft. Drain, set to one side.
In a medium saucepan heat the sunflower oil, add the mustard seeds and cumin seeds, fry on a medium heat until the cumin becomes fragrant and the mustard seeds begin to pop. Add the onions and sauté for 5-7 minutes on medium-low heat with the lid on. Now add the turmeric, coriander, garam masala, dried chillis, curry leaves, garlic and ginger. Cook for several minutes. Next add the drained split peas and the rinsed lentils. Then add the coconut milk and 750ml water and add the salt. Stir and bring to a boil, then simmer, now place the lid on. Cooking time can take 30-50 minutes.
Check the lentils are soft and cooked through, then add the fresh spinach, stir and place the lid back on and cook for several minutes so that the spinach wilts.
Crispy onion; add the sunflower oil to a medium saucepan and on a high heat add the onions. Have a plate ready lined with kitchen paper. Cook the onions until they are golden and crisp, remove with a slotted spoon and place on the kitchen paper.
Spoon the dhal into bowls, top with red chilli, coriander and crispy onions. Serve with chapatis or rice.