Boil yam with salt and water. Whiles yam is boiling, thinly chop sausages, onions, celery and garlic. Set aside.
Heat margarine or butter in a pan. Saute onions, garlic and celery till soft. Do not caramelise or brown the onions. Stir in sausages and turn off fire. Check on yam to see if it softened or cooked through. Drain off water when done.
Preheat an oven to 180℃/ 350℉. Line a baking pan with baking sheet. In a small bowl, mix cornflakes and black pepper together. Beat one egg in a different bowl, set aside.
Using a food processor, or fork or asanka with apotɔyowa mash cooked yam. Yam should be well mashed but resemble a course dough. Add in egg yolk, margarine or butter and stir together. Add in sauteed garlic, onions, celery and chopped sausages.
Bake balls in the preheated oven for about 15 minutes till the cornflakes is well stacked to the balls and looks cripsy. Serve as snack, as an accompaniment to a meal or with ketchup or shito.