For marinade, place ingredients in a blender and blend to a smooth paste. Transfer to a non-reactive container with a lid, add lamb and toss to coat well. Cover with lid and marinate in fridge overnight.

For kosha mangsho sauce, heat mustard oil in a large saucepan over medium-high heat until just starting to smoke. Add whole spices and stir until lightly toasted (30 seconds - 1 minute). Add onions, ginger and garlic, and cook, stirring frequently, until onions start to caramelise (5-6 minutes). Scatter over remaining ground spices and cook until spices are fragrant, and onion is lightly caramelised (1-2 minutes).

Add marinated lamb to saucepan and cook stirring until lightly browned and coated in onion mixture (6-8 minutes). Stir in yoghurt with 1 litre water and bring to a simmer (3-4 minutes). Reduce heat to very low, cover partially with a lid and cook, stirring frequently, until lamb starts to tenderise (1 hour). Remove lid and cook, stirring frequently, until lamb is very tender, dark brown and sauce has thickened (35-45 minutes); season to taste. If sauce starts to dry out add extra water, a little at a time.

Meanwhile, for luchi, in a large bowl, mix flour, spinach, oil, 100ml water and a pinch of fine cooking salt by hand until combined. If dough is too dry, add a little extra water 1 tbsp at a time; knead until dough is firm and smooth (5-8 minutes). Rest dough for 15 minutes. Roll dough into 25gm balls and place on a lined oven trays; loosely cover with plastic wrap and stand for a further 15 minutes.

Half fill a large saucepan with extra oil and heat over high heat to 180˚C. Roll each ball of dough to 8cm discs on a work surface. Deep-fry luchi, in batches, turning halfway, until puffed and golden (40 seconds - 1 minute each side). Drain on paper towel.

To serve, transfer kosha mangsho to a serving bowl and top with green chilli with luchi and rice on the side.