Peel and wash the potatoes and cut them roughly into pieces. Cover and cook in little boiling salted water for about 20 minutes. Wash and clean the chillies and cut into fine rings. Melt butter in a pot.
Add chili, except for something to sprinkle on top, and add wasabi. Warm the milk. Drain the potatoes and press them through a potato ricer. Add butter, except for 1 tablespoon, and milk and stir in. Season to taste with salt.
Sprinkle with chilli and sprinkle with the remaining wasabi butter.