Boston Lettuce Salad with Buttermilk Ranch Dressing

In a medium bowl, whisk together mayonnaise, buttermilk, lemon juice, salt, celery seed, oregano, black pepper, and cayenne pepper, if using.

Place lettuce leaves and cherry tomatoes in a large bowl; drizzle over dressing and toss to combine. Serve immediately. Store any remaining dressing, refrigerated in an airtight container, for up to 1 week.