If using whole spices, add chaat masala spices and cumin to a skillet over medium heat. Toast spices for 4-5 minutes, until fragrant. In a food processor or mortar and pestle, pour spices in a grind to a coarse grind and pour into a bowl. Add walnuts and crush to a coarse grind as well, then pour into bowl with spices. Stir in paprika and fleur de sel and reserve 1 tbsp of spice mixture.
Stir together 2 tbsp EVOO, mustard and reserved tbsp spice mixture in a small bowl. Rub mixture onto meat of lamb then set aside or marinate in the fridge for 30 minutes and up to 6 hours.
Preheat oven to 400*F and line a baking sheet with parchment paper. In a shallow dish, stir together panko, walnuts, remaining spice mixture. Press lamb chops into panko mixture, pressing to adhere to meat, repeating with all lamb. Preheat a non-stick pan over medium heat, and add remaining 2 tbsp EVOO to pan. Sear all lamb on each side for 3-4 minutes per side, then move to prepared baking sheet. Finish cooking lamb in oven for 7-8 minutes until it reaches 145*F for medium rare. Prepare Oregano Raita, stirring in fresh mint and serve alongside lamb.