How to Make It
Preheat the oven to 350°. On a baking sheet, toss the bread cubes with 1 tablespoon of the vegetable oil and toast for 15 minutes, stirring once or twice, until the bread is golden and crisp.
Meanwhile, in a large skillet, cook the bacon over moderately high heat, turning once, until crisp, about 6 minutes. Drain on paper towels and crumble.
In a small bowl, using the back of a spoon, mash the garlic to a paste with a pinch of salt. Whisk in the mayonnaise, buttermilk, vinegar and mustard. Gradually whisk in the remaining 1/2 cup of vegetable oil and season with salt and cayenne. Stir in the blue cheese.
In a large bowl, toss the lettuce, onion, celery, bacon and croutons with the dressing and serve right away.