Begin by adding the puy lentils to a large pan with a lid, cover with approx 3x the amount of water and bring to the boil. Turn down to a simmer and allow to cook for 30 minutes.
While the lentils are simmering, add 1 tsp of the oil to a frying pan, heat then add the onion and carrot. Cook on a low heat for 10 minutes, then add the garlic, chilli flakes, ginger, turmeric and tamarind paste, stir together before pouring in the passata and adding the chopped dates and tomatoes.
Once the lentils have cooked for 30 minutes, drain them through a sieve, return them to the pan and pour in the passata and spice mixture. Stir to combine then turn up the heat until it starts to bubble. The turn down to the lowest heat, add the lid to the pan and allow to cook for a further 15-20 minutes. Keep your eye on the pan and add a little water if needed during cooking time so the mixture does not stick to the bottom of the pan, give it a stir once during cooking time.
For the kale, clean the frying pan, then add the kale to the pan, turn the heat to a medium and gently cook the kale until it starts to crisp on the outer edges- this should take 3-5 minutes.
Serve the puy lentils with the side serving of crispy kale.