Combine the vinegar, basil, sugar, 1/2 teaspoon of salt, 1/4 teaspoon of pepper and oil in a blender and blend until smooth. Can be made 2 hours in advance and refrigerated. Bring to room temperature before using.
Combine the corn kernels, onion and tomato in a large bowl. Add the dressing and toss to coat, season with salt and pepper. Let sit at room temperature 30 minutes before serving. Top with crumbled blue cheese and garnish with basil sprigs just before serving. Salad can be made 1 day in advance and served cold or at room temperature.