"According to family legend, this recipe came from the El Gaucho restaurant in Seattle, about 50 years ago. It has been a family favorite ever since! It's a wonderful salad dressing, and a top-notch dip as well. Store in glass jars in the refrigerator."
Mix mayonnaise, sour cream, buttermilk, green onions, garlic, Worcestershire sauce, and garlic powder together in a large bowl; season with salt and black pepper. Fold cheese into the mayonnaise mixture.
Any cheese will do: feta, stilton, anything crumbly. You can also add to it over time. It keeps well in the refrigerator and is best if it has a chance to marinate a day or so. When chopping the green onions, I use the 'middle,' discarding an inch off each end, and I really chop it fine. I think this is the 'secret ingredient.'