- 1 cup walnuts
- 4 slices bacon
- 8 ounces blue cheese, crumbled, divided
- 1/2 cup crème fraîche or sour cream
- 1/2 cup mayonnaise
- 5 teaspoons sherry vinegar or red wine vinegar
- 2 teaspoons fresh lemon juice
- 1 teaspoon hot sauce
- Kosher salt, freshly ground pepper
- 1 head of iceberg lettuce, cut crosswise into four 1-inch-thick slices
- 2 celery stalks, thinly sliced
- 1 pint cherry tomatoes, quartered
- 1 tablespoon finely chopped tarragon
- Preheat oven to 350°F. Toast walnuts on a rimmed baking sheet, tossing once, until golden brown, 8–10 minutes. Let cool; coarsely chop.
- Cook bacon in a large skillet over medium-high heat, turning halfway through, until brown and crisp, 8–10 minutes total. Transfer to paper towels to drain. Let cool; crumble.
- Place half of blue cheese in a medium heatproof bowl and microwave on medium until melted, about 1 minute (this will make it easier to whisk). Add crème fraîche, mayonnaise, vinegar, lemon juice, and hot sauce to blue cheese and whisk until smooth; season dressing with salt and pepper. Cover and chill until cold, at least 30 minutes.
- Place 1 slice of iceberg lettuce on each plate and spoon about 1/4 cup dressing over each. Top with walnuts, bacon, celery, tomatoes, tarragon, and remaining blue cheese.
- Dressing can be made 3 days ahead. Keep chilled.