Ingredients

1 Yukon gold potato (3 ounces), peeled and sliced 

2 bunches fresh flat-leaf parsley, roughly chopped (2 1/2 cups chopped) 

1/2 small red onion, chopped (about 3 ounces) 

6 cornichons, finely chopped 

2 cloves garlic, finely chopped 

2 slices (each 1 inch wide) green bell pepper, finely chopped 

4 tablespoons capers 

1 teaspoon crushed red-pepper flakes 

1 cup extra-virgin olive oil 

3 tablespoons red-wine vinegar 

Salt and freshly ground black pepper 

Preparation

Place the potato in a small saucepan; cover with cold water. Place over high heat; bring to boil. Reduce heat to medium, and simmer until tender, 8 to 10 minutes. Drain, and mash very well with a fork; set aside.

Combine remaining ingredients in the bowl of a food processor, and pulse briefly until mixture is coarsely pureed. Transfer mixture to a medium bowl; whisk in reserved potato until well combined. Season with salt and pepper, cover, and transfer to the refrigerator.