Shaved Fennel, Radish, and Grapefruit Salad

Heat oil with fennel seeds in a small heavy saucepan over moderate heat until seeds are fragrant and pale golden, 1 to 2 minutes.

Remove from heat and let steep 2 hours.

While seeds are steeping, quarter fennel bulbs lengthwise and cut out and discard most of cores, leaving just enough core to keep quarters of fennel intact.

Cut fennel lengthwise into paper-thin slices with slicer.

Transfer to a large bowl.

Cut radishes crosswise into very thin slices (slightly thicker than fennel slices) with slicer and add to fennel in bowl.

Cut peel, including all white pith, from grapefruits with a small sharp knife. Working over a bowl, cut segments free from membranes and squeeze juice from membranes into bowl.

Transfer segments to a cutting board, reserving juice in bowl, and coarsely chop, then add to fennel and radishes.

Pour fennel oil through a fine-mesh sieve into a small bowl. (Discard seeds.)

Mince garlic and mash to a paste with a pinch of salt using a large heavy knife, then transfer to another small bowl.

Whisk in salt, pepper, fennel oil, and 5 tablespoons grapefruit juice, then pour over salad, tossing gently to coat.

· Fennel oil can be made 1 day ahead and chilled in an airtight container. Bring to room temperature before using.· Fennel and radishes can be sliced 6 hours ahead and chilled, covered with dampened paper towels.· Grapefruit can be chopped 6 hours ahead and chilled, covered. Chill juice separately.· Dressing can be made 2 hours ahead and kept at room temperature or chilled, covered.