Grilled Polenta Rounds with Black Bean and Avocado Salsa

For the Salsa:

black beans, rinsed and drained

ear sweet corn, kernels removed from cob

avocados, pit and skin removed, diced

tomatoes, seeded and chopped

diced red onion

small jalapeño, seeds removed and minced

chopped cilantro

Juice of 1 large lime

Salt and pepper,

For the Polenta Rounds:

tube prepared polenta

Olive oil, for brushing polenta