Place sweet potatoes in a microwave-safe dish; cover and cook on 100 percent power (high) for 5 to 8 minutes or just until tender enough to chop. Cool slightly; cut into chunks. Sprinkle lightly with salt.
In a large skillet heat oil over medium heat. Add potatoes; cook until browned and crisp-tender, about 3 minutes. Add drained corn to skillet. Cook for 3 minutes or until potatoes are tender.
Meanwhile, stir together sour cream and chipotle salsa.
To serve, divide sweet potato mixture among four plates. Top with avocado slices and serve with chipotle sour cream sauce. If desired, top with fresh cilantro and chili powder.