PLACE queso fresco and evaporated milk in blender container; process until well blended. Add 1 hard cooked egg (sliced), crackers, ají paste, garlic, palillo, lemon juice and oil; blend until smooth. Season to taste with salt, if desired. Place in bowl. Cover; refrigerate for 2 hours until chilled. Sauce will thicken while cooling.
FOLD chilled potatoes and sauce together with a rubber spatula.
TO SERVE, line large serving platter with lettuce leaves. Arrange potatoes with sauce in center. Sprinkle top with freshly ground black pepper. Place Peruvian Onion Salsa around border of plate surrounding potatoes. Garnish with olives, remaining hard cooked eggs (quartered lengthwise) and tomato wedges.
PERUVIAN ONION SALSA
COMBINE 1 medium red or yellow onion (halved and thinly sliced into half-moons, rinsed in cold water and drained), 1 to 2 hot yellow Peruvian peppers or jalapeños (seeded and minced), 1 finely chopped garlic clove, 2 tablespoons finely chopped fresh cilantro or parsley leaves, juice of 1 lemon, 1/4 teaspoon each of salt and freshly ground black pepper in small bowl. Cover; refrigerate for up to one day.
*If queso fresco is hard to find, substitute 6 ounces feta cheese and 2 ounces of cream cream cheese, mixed until combined.