Peel the beets and carrots and cut into 1/4-inch dice. Peel the potatoes and cut into 1/2-inch dice. Trim the string beans and cut into 1/2-inch pieces. Drain, rinse and pat dry the small capers, for garnishing. Pour the water in the pressure cooker. Place the diced beets, and then the potatoes, carrots, and string beans in the steamer basket on the trivet in the pressure cooker. Position the lid on the pressure cooker and lock in place. Raise the heat to high and bring to high pressure. Adjust heat to stabilize pressure and cook 6 minutes. Remove from heat and lower pressure using the cold water release method. Open the pressure cooker. If the vegetables are not yet tender, reposition the lid on the pressure cooker and cook under high pressure an additional 1 to 2 minutes. Open the pressure cooker and carefully remove the steamer basket with the cooked vegetables. Place the cooked vegetables in a large mixing bowl. Let cool until just warm. In a small bowl mix together 3/4 cup of the mayonnaise with the vinegar. Add the chopped pickles to the vegetables. Toss to mix. Add the mayonnaise dressing and toss to blend. Taste and adjust for salt. Spoon the salad on a serving plate, mounding slightly. Smooth top with a spatula and evenly spread with the remaining 1/2 cup of mayonnaise. Sprinkle the top with the capers. Recipe from Tom Lacalamita, to be featured in The Ultimate Pressure Cooker Cookbook (1997) NOTES : A pressure cooker makes this classic quicker This recipe was found on the Web Ketchum Kitchen at www.recipe.com