1 pound green beans, ends trimmed and cut on the bias into 1-1/2-inch lengths
1 pound yellow wax beans, ends trimmed and cut on the bias into 1-1/2-inch lengths
1 pound asparagus, ends trimmed and cut on the bias into 1-1/2-inch lengths
1/4 cup thinly sliced fresh chives
3 tablespoons white wine vinegar
2 teaspoons kosher salt
1 teaspoon granulated sugar
1/2 teaspoon freshly ground black pepper
1/3 cup olive oil
Prepare an ice water bath by filling a large bowl halfway with ice and water; set aside. Bring a large pot of heavily salted water to a boil over high heat.
Add green beans to the pot and cook until just tender, about 2 to 3 minutes. Remove with a slotted spoon to the ice water bath and let cool, about 4 to 5 minutes. Remove beans from the ice water bath and spread out on a clean kitchen towel or a paper towel to dry. Repeat with wax beans and asparagus, adding more ice to the ice water bath in between batches.
While the beans are drying, combine chives, vinegar, salt, sugar, and pepper in a large, nonreactive bowl. While whisking, add oil in a steady stream until completely incorporated.
Add beans and asparagus to vinaigrette and toss gently to combine. Serve at room temperature or chilled.