Salmon and Cucumber Boats

6 ounces smoked salmon, cut into 1/2-inch squares

1 large tomato (about 1/4 pound), diced

2 green onions, thinly sliced

2 tablespoons chopped fresh basil

1 tablespoon olive oil

1/2 teaspoon freshly ground black pepper

1/4 teaspoon salt

8 kirby (or Persian) cucumbers, peeled, halved lengthwise and seeded

1 1/4 cup reduced-fat sour cream

4 slices pumpernickel (or whole-wheat pitas)