Whisk the marinade ingredients in a large bowl. Add the chicken, coat well, and refrigerate for 2 to 6 hours.
Heat the oven to 425°F. Bake the chicken on a lined baking sheet for 18 to 22 minutes, until it reaches 165°F inside. Cool completely.
If using regular frozen corn, thaw, pat dry, and cook in a hot skillet with 1 teaspoon oil over medium-high heat for 5 to 7 minutes, until lightly charred. Cool.
Finely shred the chicken using a stand mixer with the paddle attachment on low, or pulse in a food processor.
In a small bowl, stir together the mayo, adobo sauce, lime juice, sugar, and salt.
Add the corn, sun-dried tomatoes, bell pepper, and shallot to the chicken. Fold in the dressing until evenly coated.
Refrigerate for at least 1 hour. Taste and adjust salt or adobo sauce before serving.