Slice the grapefruit in half; place each half onto a cutting board, skin side down.
Using a sharp knife cut around the perimeter of the grapefruit so that the peel and white pith is separate from the fruit all the way around.
Starting at the middle of the fruit, cut on either side of each white line membrane so that you're effectively loosening and removing each wedge of fruit from the membrane.
Place the grapefruit, salad leaves, cucumber and snow peas in a bowl and toss to combine.
Drizzle over the balsamic vinegar and serve.