This lively oil and vinegar-based salad dressing is easily prepared ahead. Toss the beans with the dressing just before you leave for the picnic.

2 Tbsp. cider vinegar

1 small shallot, minced

1 tsp. Dijon mustard

1-2 tsp.kosher salt

6 Tbsp.extra-virgin olive oil

1 1-2 Tbsp.boiling water

1 pound green beans, washed and trimmed, cut into 1-inch pieces

1-2 small red onion, thinly sliced

2 Tbsp. chopped flat leaf (Italian) parsley

In a blender or small food processor combine the cider vinegar, shallot, mustard and salt to taste. Blend for a few seconds then, with the blender still on, gradually add the olive oil until blended, and then mix the boiling water into the dressing.

In a large pot of boiling salted water, cook the green beans just until tender, about 4 minutes. Drain the green beans in a colander and then place in ice cold water to stop the cooking. Drain and dry with a clean towel.

In a large bowl, toss the cooled green beans, red onion and parsley with the dressing.

The cider dressing and the blanched green beans can be refrigerated separately in airtight containers overnight. Let the green beans return to room temperature before making the salad.

Serves 6.