| 1/4 cup plus 3 tablespoons whole-grain mustard |
| 1/2 cup extra-virgin olive oil |
| 1/3 cup chopped fresh dill |
| 2 garlic cloves, minced (1 tablespoon) |
| Coarse salt and freshly ground pepper |
| 2 chicken cutlets (6 ounces each) |
| 1 large red onion, sliced into 1/2-inch-thick rounds |
| 3 ounces aged cheddar cheese, thinly sliced |
| 1 baguette, cut crosswise into 4 pieces and halved horizontally |
| 3 tablespoons creme fraiche |
| 3 sour pickles, thinly sliced lengthwise |