In a small saucepan, bring the vinegar, 1 cup of water, sugar, salt and peppercorns to a boil over medium heat, stirring until the sugar and salt dissolve.
Remove from heat, separate the shallots and add to a large mason jar then pour the vinegar mixture over the top.
Close the jar and let sit for at least 1 hour before using. Refrigerate for up to 2 weeks and drain before using.
For the corn:
Heat a large cast iron pan over medium heat, add the oil and heat through. Add the shallot and serrano pepper and sauté until the shallots are soft, about 4 minutes. Add the corn and cook, stirring occasionally, until the corn is tender, about an additional 6 minutes.
In a small bowl stir together the paprika, thyme, cumin, all-spice and cinnamon. Add the spice mixture to the coconut milk, stirring to combine. Continue to cook over medium-low heat, stirring occasionally, until the coconut milk has reduced, about an additional 10 minutes.
Stir in a generous forkful of the pickled shallots. Add to a serving bowl and top with the toasted coconut and green onion.
Notes
Make extra pickled shallots. The quick-pickled shallots are one of the best parts of this dish because their acidity balances the rich coconut milk and sweet corn. Since they keep refrigerated for up to two weeks, make the full batch and use the extras on tacos, sandwiches, salads, grain bowls, or grilled meats.