Every summer I create at least one salad that becomes my go-to. One year this was it. It's the perfectly sidekick for grilled steaks or lamb, but the ridiculously good buttermilk ranch makes this super-fresh salad satisfying on its own. All the crisp beans and peas get caught in the crunchy Boston lettuce, which entices you to eat with your hands. And not only do I condone that, I recommend it! Promise I won't tell.
Fill a medium saucepan with water and bring to a boil over high heat, then add a generous pinch of salt. Fill a large bowl with ice and water. Add the haricots verts to the boiling water and cook until crisp-tender and bright green, 2 to 3 minutes. Using a slotted spoon, transfer to the ice bath to cool. Add the snap peas and peas to the boiling water and cook until crisp-tender and bright green, 1 to 2 minutes. Drain well and transfer to the ice bath to cool. Drain the beans and peas very well and then pat dry with paper towels, or give them a whirl in the salad spinner.
In a medium bowl, whisk together the buttermilk, mayonnaise, minced chives, dill, garlic powder, and onion powder. Season the ranch dressing generously with salt and pepper.
In a large serving bowl, toss the beans and peas with the lettuce, the snipped chives, and half the ranch. Season the salad with salt and pepper. Serve right away, passing additional ranch at the table.
Do It Ahead: The cooked beans and peas can be covered with a damp paper towel and refrigerated overnight. The ranch can be refrigerated in an airtight container for up to 5 days.