Heat 1 Tbsp. olive oil in skillet; add corn and cook until soft, then reserve. Heat remaining 2 Tbsp. oil in skillet; when hot, add onion and cook until translucent. Add rice and cook for one more minute. Add white wine and cook on medium until nearly gone; continue to add stock one cup at a time while stirring until liquid cooks off. When all liquid is incorporated and rice is tender (approximately 30 minutes), stir in Parmesan cheese, salt, and pepper. Chill this mixture.
To make arancini, form small balls of the risotto mixture with your hands. Fit one small cheese cube in the center of each ball. Roll each ball in egg, then breadcrumbs. Fry in small batches until balls are golden brown.
Serve with salsa of fresh corn, diced tomatoes, and chopped cilantro.