To prepare tomatoes, sprinkle the tomato slices evenly with 1/4 teaspoon salt and 1/8 teaspoon black pepper. Dredge tomato slices in cornmeal.
Heat 2 teaspoons oil in a large nonstick skillet over medium-high heat. Add 6 tomato slices to pan, and cook 2 minutes or until lightly browned. Coat tops of tomato slices with cooking spray; turn slices over. Cook for 2 minutes or until lightly browned. Remove from pan. Repeat procedure with the remaining 2 teaspoons olive oil, remaining 6 tomato slices, and cooking spray.
To prepare salsa, return pan to medium-high heat. Coat pan with cooking spray. Add onion and bell pepper; sauté 3 minutes. Add corn and garlic; sauté 1 minute. Stir in vinegar, 1/4 teaspoon salt, and 1/8 teaspoon black pepper. Remove from heat; stir in parsley. Serve warm salsa over tomato slices.