Make vinaigrette: mix honey with mustard and flaxseed oil. Arrange lettuce on plates, sprinkle lightly with salt. Add peeled and cut avocado pieces, drizzle with vinaigrette.
Peel grapefruit, separate into segments and remove the flesh from the surrounding membranes, arrange on salad. Add pomegranate seeds. Drain crab and press well, add to salad, sprinkle with black seeds and serve immediately.