Place the frozen corn in a microwave safe container, microwave on high for one minute, and then blot with a paper towel to remove excess water. Set aside to cool completely.
Make the lime citrus vinaigrette. In a small bowl whisk together the lime juice, olive oil, agave, cumin, salt, and pepper. Set aside.
Cut the top off of each of the four peppers. Remove the stems, ribs and seeds from each pepper and then chop the tops only.
Rinse and drain the black beans and add to a big bowl along with the chopped pepper tops, corn, avocado, grape tomatoes, and scallions.
Re-whisk the lime vinaigrette and pour over the black bean mixture. Combine thoroughly.
Spoon some of the black bean salad into each of the four peppers and garnish with cilantro if desired.