The vendor told me as soon as the dark beans "get heated up" they turn dark green and they tasted just like a regular green bean.
I bought them anyway and lo and behold, they did lose their purple color, they were a darker shade of green than the other green beans.
No doubt these beautiful beans would be perfect as a summer salad.
1/2 lb. each of your favorite three fresh whole green beans totaling 1-1/2 lbs of whole green beans
Trimmed, rinsed and drained
1 small red onion roughly chopped
1 tablespoon Dijon mustard
1 lemon, juiced (approximately 1/4 cup)
1/3 cup extra virgin olive oil
Pinch of sugar
Kosher salt and freshly ground black pepper to taste
Blanch the beans in a large pot of salted, boiling water for 3 minutes. Immediately drain the beans and transfer them to a large bowl of ice water to stop the cooking process. This will also allow the beans to maintain their crispiness. Leave the beans in the ice water for a couple of minutes to cool them off, the drain them thoroughly in a colander.
In a bowl or Mason jar, whisk together or shake the Dijon mustard, lemon juice and sugar. Then add in the olive oil and whisk or shake the jar vigorously to emulsify.
Place the beans and onions in a large bowl, toss together to combine. Drizzle the dressing over the beans and toss again to evenly coat the beans with the dressing. Season with salt and pepper to taste.
Cover and refrigerate for at least 2 hours, actually, the longer the beans can marinate in the dressing, the better they will taste.
I need to make this one more time before the hot weather leaves us this season!