Prepare the ingredients: Cut the chicken into 1/2-inch (1.5cm) strips. In a large bowl combine 1 tablespoon of oil and Fajita seasoning, add the chicken, season with salt and pepper, and toss to combine.
Cut bell peppers into 1/4-inch (7mm) strips, cut the onion in half then into 1/4-inch (7mm) slices. Peel and slice the avocado.
Cook the chicken: Heat the remaining oil in a large frying pan over high heat. When hot add the chicken (in one or two batches, depending on the size of the pan). Cook until browned then turn over and cook until cooked through, transfer to a plate, drizzle with lime juice.
Cook the vegetables: Reduce the heat to medium-high and add the bell peppers and onions, season with salt and pepper. Cook for a couple of minutes or until softened but still a little bit crunchy.
Make the sauce: in a food processor or blender mix the cilantro (only the leaves and tender stems), yogurt, lime juice, sour cream, about 1/2 cup of sauteed bell peppers and onions, and half of an avocado, until smooth. Season to taste with salt and pepper.
Assemble: Arrange all the ingredients in two bowls - rice, cooked chicken with bell peppers and onions, drained and rinsed beans and corn, sliced avocado, pour over the sauce.