Cook the green beans in a small saucepan of boiling, lightly salted water for 6-8 minutes until crisp-tender.
Drain immediately and rinse under cold water to cool.
Drain well.
In an extra-large bowl, combine the cooled green beans, chopped lettuce, tomatoes, cucumber, corn, chopped eggs, carrot, cheese, and red onion.
To make the dressing, whisk together the buttermilk and mayonnaise in a small bowl until smooth.
Stir in the green onion, minced garlic, and salt until well combined.
Drizzle the dressing over the salad and toss gently to coat all the .
Serve immediately for the best crunch.