Ingredients

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 

Preparation

Mix 1/4 cup mustard, the oil, dill, garlic, 1 1/2 teaspoons salt, and 3/4 teaspoon pepper in a medium bowl. Add chicken and onion, and toss to coat. Refrigerate, covered, for 30 minutes.

Preheat grill to medium-high. Grill onion, turning often, 8 to 10 minutes. Grill chicken on 1 side for 3 minutes; flip, top with cheddar, and cook 3 minutes more. Cut cutlets in half. Grill baguette, cut sides down, until crisp, 1 to 2 minutes.

Mix remaining 3 tablespoons mustard and the creme fraiche in a small bowl. Spread onto cut sides of baguette. Sandwich chicken, pickles, and onion between bread.