- 1/2 cup plain Greek-style yogurt
- 1 tablespoon bottled white horseradish
- 1 3/4 teaspoon grainy mustard
- 1/2 tablespoon fresh lemon juice
- 1 seedless cucumber, peeled and halved crosswise
- 1/4 large sweet onion
- 7 to 8 ounces hot-smoked salmon, mackerel, or trout
- Equipment: an adjustable-blade slicer
- Accompaniment: bagel chips (optional)
- Whisk together yogurt, horseradish, mustard, and lemon juice. Season with 1/4 teaspoon salt.
- Cut thin ribbons of cucumber with slicer, then very thinly slice onion. Toss with half of yogurt sauce.
- Discard skin from fish and break fish into large flakes. Arrange fish on cucumber-onion mixture and serve with remaining sauce.