This is a delicious salad featuring capers and a sherry vinaigrette.
Cover beans, onion, celery, and carrot with water in a large saucepan. Bring to a boil, then reduce heat and simmer until tender but not falling apart, 35 to 40 minutes. Season with salt. Drain; discard vegetables. In a large bowl, toss beans with 1/4 cup oil and the vinegar. Let cool slightly.
Meanwhile, heat oven to 450 degrees. On a rimmed baking sheet, toss artichoke hearts with remaining 2 tablespoons oil. Roast, flipping once, until golden brown and crisp, 15 to 20 minutes.
Add to beans with capers and parsley. Season with salt and pepper flakes and drizzle with oil. Serve warm or at room temperature.
