1. Melt butter in an oven safe pan or heavy skillet and add cornbread. Toss in butter and cook over medium high heat for 3-5 minutes. Toast in a preheated oven at 300 degrees for 10-15 minutes or until dry and hard like croutons. Remove from oven and set aside until cool.
2. Whisk together olive oil, balsamic vinegar, mustard, zest and maple syrup. Salt to taste.
3. In a large bowl, toss cornbread with tomatoes, onion, cucumber and basil. Drizzle with 1/3 to 1/2 of the dressing and serve the rest on the side.