- 1 onion, cut into paper-thin slices
- 2 1/2 teaspoons grainy Dijon mustard
- 2 teaspoons red or white wine vinegar
- 1/4 teaspoon salt
- 1/4 teaspoon fresh-ground black pepper
- 1/2 cup olive oil
- 1 pound sliced smoked ham, such as Black Forest, cut into matchstick strips
- 1/2 pound sliced Gruyere cheese, cut into matchstick strips
- 3/4 cup chopped fresh parsley
- Put the onion in a small bowl of cold water and let stand for 10 minutes. Drain the onion, rinse, and then pat dry with paper towels.
- Meanwhile, in a large glass or stainless-steel bowl, whisk together the mustard, vinegar, salt, and pepper. Add the oil slowly, whisking. Add the ham, cheese, onion, and parsley to the vinaigrette and toss.