Place the red onion in a small bowl, add the vinegar, and soak for at least 30 minutes.

Lay the peppers on a baking sheet and broil for ten minutes per side, or until blackened. Remove from the oven and place in a bag for 15 minutes. Remove, and when cool enough to handle, carefully peel off the skin, keeping peppers intact. Using a small knife, cut a slit from the stem to the pointed end of each pepper, leaving one inch on either end uncut. Using a small spoon, remove all of the seeds and top pith just under the stem. Set aside.

Slice the corn kernels from the ears of corn. Bring ½ cup lightly salted water to a simmer in a small pan over medium heat. Add the corn kernels, and simmer until tender (about 2 minutes). Place in a medium bowl.

Preheat the oven to 350˚F. Add the red onion and any red wine vinegar not absorbed to the corn, along with the cilantro, half of the cheese, olive oil, salt, pepper and cayenne. Toss together.

Divide the corn mixture evenly between two bowls, and add coarsely chopped shrimp (if using) to one of the bowls.

Line a baking sheet with parchment paper and place the peppers on the paper. Carefully spoon the filling into each pepper so that two peppers are filled with the vegetarian corn mixture; the other two with the shrimp and corn.

Bake for ten minutes. Top the peppers with the remaining cheese and lime juice. Lightly mix in using a spoon. Bake another five minutes, or until the cheese has melted. Serve warm.

Lightly salt and pepper the shrimp and bring to room temperature.

Heat enough olive oil to cover the base of the pan over medium-high heat. Sauté shrimp by cooking on one side for two minutes; turn the shrimp over and cook an additional minute. The shrimp should be curled up and fairly firm to the touch.

Squeeze the lime juice over the shrimp and toss in the pan. Remove the shrimp and coarsely chop.