It's evident how Mary's garden grows when you taste this salad, which has a mix of tender lettuces and an herb-filled buttermilkdressing made with fresh parsley, dill, and mint.
Preheat oven to 350 degrees. Toast brioche cubes on a baking sheet untilgolden, 5 to 6 minutes. Let cool.
Meanwhile, whisk together buttermilk, sour cream, vinegar, sugar, and 1/2 teaspoon salt in a large bowl. Gradually whisk in oil, then cheese and herbs. Add lettuces, and toss to combine. Garnish with brioche croutons.
Croutons can be stored in an airtight container at room temperature for up to 1 day.