1. Remove peel and pith from grapefruits with a sharp knife. Working over a large bowl, carve out segments from between membranes, allowing them to drop into bowl. Refrigerate until ready to use.

2. Whisk egg yolks, honey, 1 tablespoon water, the lemon juice, and salt in a heatproof bowl. Set bowl over a pan of simmering water; whisk vigorously until doubled in volume, about 10 minutes.

3. Meanwhile, put cream into the bowl of an electric mixer fitted with the whisk attachment. Beat on medium-high speed until stiff peaks form. Remove yolk mixture from heat. Using a rubber spatula, gently fold whipped cream into yolk mixture until combined. Refrigerate zabaglione 15 minutes.

4. Divide the grapefruit sections among serving dishes. Spoon zabaglione over top of grapefruit.