Green Bean Salad with Walnuts

12 walnuts in the shells

2 teaspoons coarse mustard

1/4 cup Basic Lemon Vinaigrette ( recipe follows )

1 tablespoon walnut oil

1 tablespoon chopped chives

Fleur de sel

Zest of 1/2 large lemon

1 small or 1/2 medium shallot, minced, rinsed with cold water, and drained on paper towels

2 tablespoons strained freshly squeezed lemon juice

1 1/2 teaspoons white wine vinegar or champagne vinegar

1/4 teaspoon kosher salt

1/8 teaspoon cracked black peppercorns

1/4 cup canola oil

1/4 cup extra virgin olive oil