Direction :

1. Preheat oven to 425° F. Slice eggplants lengthwise into 1/4-inch thick strips and lay strips on an oiled or parchment- or Silpat-lined baking sheet.
2. Mix balsamic vinegar and olive oil in a dish. Brush vinegar-oil mixture across top of each slice of eggplant. Then sprinkle with salt and pepper over the top. Roast for about 10 minutes. Turn slices over, brush with oil mixture, season with salt and pepper, and roast for another 8 minutes or so. Cool.
3. Cut baguettes lengthwise in half and spread each half generously with the softened butter.
4. Place eggplant slices on the bread and top with arugula leaves. Close sandwiches and serve.