Peel, wash and chop the potatoes and sweet potatoes. Cover with cold water and put aside. Wash the rack of lamb and pat dry. Froth 75 g butter in a saucepan briefly and let it cool down a little.
Cut toast bread into pieces and chop finely together with the macadamia nuts in the universal chopper. Wash the parsley and mint, dab dry and chop as well, except for a little to garnish.
Stir the herbs and the nut bread mixture into the butter and season with salt and pepper. Peel onion and garlic. Dice onion, press garlic through a garlic press. Heat the oil in a frying pan or a large ovenproof pan and fry the lamb loins briefly and thoroughly, turning them over.
Season with salt and pepper and remove. Briefly braise onion and garlic in hot frying fat, stir in paprika purée and deglaze with stock and white wine. Stir in crushed chilli and soy sauce, bring to the boil briefly.
Place the herb-nut mixture on the top of the squares and press down well. Put the squares back into the pan. Roast in the preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: level 4) for 15-20 minutes.
Cook the potatoes and sweet potatoes in boiling salted water for about 15 minutes. Clean and wash spring onions and cut into 2-3 cm long pieces. Heat 50 g butter and sauté the spring onions for about 3 minutes.
Remove the onions and put the fat aside. Drain the finished potatoes, collect the cooking water and measure approx. 125 ml. Add to the potatoes again, mash and stir in the onion frying fat.
Let the finished rack of lamb rest for about 5 minutes. Then cut into individual chops and arrange on plates with the sauce and mashed potatoes. Spread spring onions on the puree and serve garnished with mint.