The flavors of this classic American dressing are very similar to those of tartar sauce and gribiche. Serve it with salad greens, steamed vegetables, sliced hard-cooked eggs, potatoes, or tomatoes, or chilled seafood.
1Combine the mayonnaise, cornichons, mustard, parsley, tarragon, capers, garlic, and vinegar in a blender or mini-food processor and process just until combined. While the machine is running, add the oil in a thin, steady stream, and process until the dressing thickens and is fairly smooth. Season with salt and cayenne. Will keep, tightly covered, in the refrigerator for up to 5 days.