Direction :

1. Slice off the end of each orange. Squeeze the juice from each end into a large bowl. Working with one orange at a time, stand it on its flat end. Use your knife to slice down around the orange to remove the skin. Hug the flesh as you slice—it’s better to lose some flesh in the rind than to have pith clinging to the flesh. Squeeze the rinds into the large bowl. Turn the orange on its side and slice down crosswise to create 1/2-inch thick slices. Repeat with remaining orange. Place orange slices in the bowl with the squeezed juice.
2. Peel the grapefruit in the same fashion, but instead of slicing it into rounds, remove each segment by running a knife along the white membrane holding each segment in place. Drop each segment into the bowl with the oranges and juice. Once the segments have all been released, squeeze what’s left of the grapefruit over top.
3. Slice each endive in half through its core; then cut crosswise to create 1-inch wide pieces. Place the endive in the bowl with the citrus.
4. Halve the avocado, remove the pit, cut the flesh into slices, then add to the bowl with the citrus. Season with sea salt and the 1 tablespoon of white balsamic vinegar. Toss gently with your hands. Add the Boston lettuce and toss gently again with your hands.
5. Transfer the salad, again using your hands, to a large serving platter. (Note: Using your hands is important because it’s such a delicate salad. You want to preserve the integrity of each of the components as much as possible, so a gentle toss is critical.) Season all over lightly with sea salt and pepper to taste. Drizzle all over with olive oil to taste. Shave Parmigiano Reggiano over top using a vegetable peeler. Crack more pepper over top if you wish. 
6. Serve with a knife and fork.