First, prepare the dressing.
In a small bowl, whisk together the mayonnaise, sour cream, and olive oil until smooth.
Squeeze in the juice of two limes, add the minced serrano chiles, and sprinkle generously with salt and pepper.
Whisk again and set aside.
Assemble the salad on a large, deep platter. Start by arranging the tomato slices in a single layer. Evenly spread the grated jícama over the tomatoes. Follow with a layer of orange slices, then the paper-thin red onion. Gently arrange the avocado slices on top as the final layer.
Just before serving, drizzle the salad with about 1/4 cup (960 ml) of the prepared dressing.
Garnish with fresh cilantro and the remaining lime cut into wedges.
Serve immediately, passing the remaining dressing at the table.