Cut the potatoes in middle sized pieces, then cook them in water.
When the potatoes are cooked, purify them so that they form a homogeneous mass. Salt and pepper to taste and add the butter and nutmeg.
Melt the butter and add the flour. Mix everything to remove lumps. Poor the water to the mixture and mix.
Add the grounded pepper, the vinegar and some salt.
Put oil in a pan and let it heat. Add the beef and sauté. Salt and pepper. When the beef has finished cooking, ad the pepper sauce to it.