Cucumber, corn, and smoked salmon salad with mustard maple vinaigrette

1 medium English cucumber
4 medium red potatoes
1 1/2 cups corn kernels
1/2 pound smoked salmon
1 cup cherry tomatoes
2 to 3 tablespoons coarsely chopped fresh dill
8 ounces prewashed salad greens of choice
3 to 4 tablespoons fresh lemon juice (about 1 extra large or 2 medium)
1 tablespoon Dijon mustard
2 teaspoons pure maple syrup
9 to 12 tablespoons extra virgin olive oil
Salt and freshly ground black pepper

1. Peel the 1 cucumber. Cut the 4 potatoes and cucumber into uniform 1/2-inch cubes. Place the cucumber cubes in a bowl.
2. Place the potatoes in a microwave-safe bowl with 2 teaspoons water and cover. Cook the potatoes in a microwave oven on High 4 minutes; let the potatoes stand, covered, 3 minutes. Stir the potatoes, cover again, and cook another 3 minutes; let the potatoes rest 2 to 3 minutes before removing.
3. Dice the 1/2 pound smoked salmon into 1/2-inch pieces and add to the bowl with the cucumbers. Rinse the cherry tomatoes, slice them in half, and place in a small bowl. Discard any thick stems on the dill sprigs. Chop the dill. (Some thinner stem is fine to include.) Add the chopped dill to the cooked potatoes and toss gently.
4. Squeeze 3 to 4 tablespoons juice from the lemon into a small bowl or blender. Add the mustard and maple syrup and whisk to combine. Whisking constantly or with the machine running, slowly, in a thin stream, pour in the olive oil. Taste the dressing after adding the 9 tablespoons and add more of the remaining 3 tablespoons to taste. Season with salt and pepper.
5. Toss the dilled potatoes with 2 tablespoons of the dressing. Divide the salad greens among 4 dinner plates, mounding them high. Arrange the dilled potatoes, cucumber and smoked salmon, corn kernels, and tomatoes on top. Drizzle vinaigrette over the salads; serve any remaining vinaigrette separately in a bowl.