Clean and wash the peppers and spring onions. Cut vegetables into 3-4 cm pieces, sausage into approx. 1.5 cm thick slices and halve. Put vegetables and sausage alternately on the skewers.
Fry skewers in 2 tablespoons of oil all around. Remove from the pan and keep warm. Cut onions into rings and brown in 2 tablespoons of butter. Wash parsley, dab dry and chop.
Melt the rest of the butter in a small saucepan. Keep 2 tablespoons of parsley for garnishing, add the remaining parsley to the butter. For the mashed potatoes bring 1/2 litre of water and salt to the boil.
Take the pot from the heat and add the milk. Stir in the purée flakes briefly. Let stand for 1 minute and stir again. Arrange 2 skewers on each side and arrange with mashed potatoes on 4 plates. Pour parsley butter and onion rings over the puree.
Sprinkle with the remaining parsley and the coloured pepper. Garnish with parsley.