Grapefruit and avocado is one of my all time favorite combinations. Years ago, before I had a family to feed, a sliced avocado and a carefully segmented grapefruit with a little sea salt sprinkled on top could pass for dinner. No one else in the house would find that satisfactory these days, so now it becomes part of a tossed salad with a little sliced cucumber thrown in as well. I collect the grapefruit juice while segmenting the fruit and use it with a little olive oil and salt and pepper to make the dressing.