Makes: 8 servings. PREP: 10 minutes.
Peel 3 oranges with a knife, taking care to remove the white outer membrane. Hold the orange and cut membranes away from inner sections of fruit. Set orange sections aside; cover with plastic wrap and refrigerate for several hours, if desired.
Squeeze juice from remaining orange and lemon into small bowl. Whisk with sugar, cinnamon, salt and oil. Place walnuts in nonstick skillet and toast over low heat a minute or so until fragrant and slightly crisp. Remove from heat and set aside. Can be prepared several hours ahead.
To serve, whisk dressing. Place lettuce in large serving bowl; toss with dressing and adjust seasonings if needed. Top with orange segments, walnuts and cilantro.