Ingredients

1 1/2 pounds small red potatoes

Salt and pepper

3 tablespoons olive oil, divided

4 slices crusty bread

1/2 English cucumber, halved and thinly sliced

5 tablespoons 2 percent plain Greek yogurt

2 tablespoons chopped fresh dill

1/2 teaspoon lemon zest plus 3 tablespoons juice (from 2 lemons)

1/2 pound smoked trout, flaked

1 small head romaine lettuce, leaves separated

2 tablespoons whole-grain mustard

Preparation

In a medium pot, bring potatoes to a boil in salted water over high; reduce to a simmer and cook until tender when pierced with a knife, 10 minutes. When cool enough to handle, halve potatoes.

Meanwhile, heat broiler. Brush 1 tablespoon oil on one side of each bread slice. Broil, oil side up, until crisp and lightly browned. Combine cucumber, yogurt, dill, and lemon juice; season with salt and pepper. Gently stir in trout. Top each bread slice with a few lettuce leaves and trout salad.

In a large bowl, whisk together remaining 2 tablespoons oil, lemon zest, mustard, and 1 tablespoon hot water. Add potatoes and toss to combine. Season with salt and pepper and serve with open-faced sandwiches.