Preheat oven to 300°F. Place oatmeal on a baking sheet, with sides, in preheated oven.
Toast, stirring frequently, for about 20 minutes until lightly browned. Remove from oven and allow to cool.
Place in a heat proof bowl. Cover with boiling water. Allow to sit for about 20 minutes or until just tender but not gummy. Drain off excess liquid. Place drained oats in a clean kitchen towel and tightly squeeze to remove any remaining moisture.
Combine chicken, oatmeal, onion, jicama, peppers, cilantro, garlic and jalapeno in a mixing bowl.
Whisk together mayonnaise and sour cream. Beat in lime and orange juice and stir into chicken mixture. Taste and adjust seasoning with salt and pepper.
Cover and refrigerate for about 30 minutes to allow flavors to blend. Serve on a bed of lettuce.