Adapted from Smitten Kitchen
2 lbs small new or fingerling potatoes
1 lb asparagus
1/4 lb sugar snap peas, green beans or other spring pea
4 radishes, thinly sliced
Pickled spring onions
3 spring onions (about 6 ounces)
1/4 c. white wine vinegar
1/4 c. water
1 Tbsp. kosher salt
1 1/2 tsp. sugar
Sharp mustard vinaigrette
1/4 c. olive oil
2 Tbsp. whole grain mustard
2 tsp. smooth Dijon mustard
2 Tbsp. white wine vinegar
Salt and freshly ground black pepper to taste
Boil potatoes covered with an inch of water for about 15 minutes. Poor off water and allow potatoes to cool to room temperature. Cover with cold water if necessary.
Whisk together vinegar, water, salt and sugar in a small container with a lid. Allow the salt and sugar to dissolve. Slice the spring onions into thin discs, reserving the greens, and submerge them in the vinegar solution. Cover and refrigerate until needed. Pickling the onions over night improves the flavor.
Bring salted water to boil in the same large sauce pan used for the potatoes. Fill a large bowl with water and ice to create an ice bath. Cut the tough ends off the asparagus. Add the asparagus to the boiling water. After one minute, add in the sugar snap peas. Two minutes later remove the vegetables from the boiling water and submerge them in the ice bath until chilled. Drain and pat dry to remove excess water.
Cut Asparagus and sugar snaps into 1/2 inch pieces. Place into a large salad bowl. Cut potatoes into bite-sized chunks, thinly slice the radishes on a mandolin, and chop a small amount of the reserved onion greens. Add all vegetables to the salad bowl.
An hour before serving, whisk dressing ingredients together and poor over vegetables, tossing to coat. Stir in slices of pickled onion to taste. Season with salt and pepper.