Combine first 3 ingredients in a nonmetal dish; set aside.
Grate 1 1/2 teaspoons rind from oranges; set aside. Peel and section oranges, reserving juice and membranes. Add sections to cucumber mixture. Squeeze membranes to extract juice; discard membranes. Measure reserved juice; add commercial orange juice, as needed, to equal 3/4 cup. Add rind, vinegar, sugar, and oil; stir well with a wire whisk. Pour over cucumber mixture; cover. Marinate in refrigerator 2 hours. Toss with romaine.