Peel, wash and roughly chop the potatoes and celery. Cook in boiling salted water for about 20 minutes. Heat oil in a pan and fry sausages at medium heat for about 8 minutes while turning. Peel onion and cut into strips
Clean, wash and cut the spring onions into rings. Take the sausages out of the pan and keep them warm. Sauté onion strips in the frying fat for about 5 minutes, season with salt and pepper. Dust with flour. Add stock while stirring, bring to the boil and add the sausages to the sauce
Bring milk and butter to the boil. Drain potatoes and celery. Add milk butter and mash potato-celery mixture. Season to taste with salt and nutmeg. Stir in spring onions. Arrange mashed potatoes, sausages and sauce