2 tablespoons olive oil
2 large onions, chopped, about 4 cups
1/2 cup mayonnaise (low-fat Hellman’s is perfect but the inspiring recipe called for 3/4 cup)
1/2 cup sour cream (or 3/4 cup if you like)
2 teaspoons Worcestershire sauce
Horseradish to taste (I used about a tablespoon of mild horseradish)
Fresh garlic to taste (I used a teaspoon of minced garlic)
Salt & pepper to taste
Heat the olive oil on MEDIUM HIGH in a large kettle until shimmery. Add the onions and stir to coat with fat. Cook, stirring every so often, until the onions darken and turn golden, about 45 minutes. Let cool a bit. Stir in the remaining ingredients. Transfer to a serving dish and let chill for a couple of hours to let the flavors meld.