Valpolicella Ripasso (Italy)
Syrah/Shiraz
Côtes du Rhône (France)
Merlot
Rioja (Spain)
Barbera (Italy)
Chianti (Italy)
Bordeaux Right Bank (France)
Calf liver with onions and fried potatoes is an American classic dinner and as "Fegato alla Veneziana" (Venetian liver and onions) a delicacy from the Venetian Cuisine.
Liver and onions are sweet, so we need a wine with matching sweetness.
To complement the iron flavor of liver go for a Syrah or its blends from Côtes du Rhône, a Merlot or a Rioja, they have just the right bite.
"Fegato alla Veneziana" calls for a local wine: Valpolicella Ripasso.
If there is Madeira or fortified wine in the gravy, then you need more sugar in the wine. Try an off-dry Alsatian white wine.