Preheat the oven to 190'C.
Season the lamb fillets with salt and pepper. Heat a frying pan until hot and add a drizzle of oil. Cook the lamb for around 3 minutes and until browned on all sides. Transfer to the oven and cook for another 5 minutes. Remove from the pan and allow to rest. Reserve the pan and any juices from the lamb for later.
Heat a saucepan over a medium heat and add the butter. Sweat the shallots until soft and then add the garlic. Cook for a minute and then add the peas. Season with salt and pepper and stir in the crème fraiche. Bring to a simmer and then finish the sauce with the chopped fresh mint. Add any resting juices from the lamb to this sauce.
Peel the potatoes, cut into thin slices on a mandolin and then cut into 5 centimeter wide rings with a pastry cutter. Melt the butter and then dip the potato rings into the butter, arrange in a circle approximately 10 centimeters in diameter on a non stick baking sheet, season and cook in the oven for 12 to 15 minutes or until golden in colour. Remove from the oven until needed.
Place spoonfuls of the sauce onto the bottom of a plate, carve the lamb on an angle into 5 slices and arrange in a circle on top of the sauce, then top with the potato ring.
«Add some extra flavour by dusting the potato galette with grated Parmesan just before baking.»