*Substitute low-fat sour cream for yogurt, if desired.
Combine rice, tomato, parsley, onions, mint, garlic, yogurt, lemon juice, oil, and pepper in large bowl. Cover and chill. Cut each cucumber crosswise into 1/2-inch slices; hollow out center of each slice, leaving bottom intact. Fill each cucumber slice with scant tablespoon rice mixture.
Tip
Use 1/2 teaspoon measuring spoon to scoop seeds from cucumber.