Preheat oven to 450ºF. Line a baking sheet with foil.
In a large mixing bowl, toss corn, jalapeños and onion with oil then spread evenly out onto the baking sheet. Transfer to the oven and roast for 15-20 minutes, until vegetables are lightly browned.
When cool, peel the jalapeños, if desired, then finely chop them with the onion. Reserve them with the roasted corn.
In a large mixing bowl, coarsely mash avocados with lime juice. Stir in the roasted vegetables, cilantro and Garlic Chipotle Sauce, and serve.