there are a number of variations: colcannon - potato, onion, cabbage, (carrot)
champ- potato
coddle- potato, onion, sausage/bacon
Various salsas go with both. Chimichuri sauce, pesto, steak sauce, grilled or caramelized onions, sauteed mushrooms, Bearnaise sauce, etc. If you mean side dishes, potatoes are always a good choice. Fixed any way you like. Salad, green vegetables, corn, and almost any other vegetable.
Potatoes, onions, pinto beans, and apples are four such crops.
Casino butter is simply a compound butter that is a mixture of unsalted butter and parsley, green onions, garlic, red bell pepper, hot sauce, white wine, lemon juice, salt & pepper.
potato
I'm not sure exactly what you mean by white sauce. The most common sauce referred to as white sauce is "alfredo sauce" made from a mixture of butter, heavy cream, and Parmesan cheese. It could also refer to any number of white wine based sauces, cheese or cream based sauces or chowders, etc.
beef stroganoff
The flour used in the making of white sauce thickens as it cooks in the milk. Flour is used the thicken a lot of soups, stews, and sauces.
Chicken Blanquette
Another name for green onions is scallions.
A bunch of onions
pink sauce
Another name for Yukon Gold potatoes is yellow potatoes.