For the onions:

1 1/2 cups white vinegar

1/2 cup sugar

2 bay leaves

2 cups water

2 medium red onions, thinly sliced into rings

1/2 cup Wondra flour (also called instant flour)

1 teaspoon ground dry mustard

1/2 teaspoon salt

1 cup vegetable oil

For the burgers:

1 1/2 pounds 85 percent lean ground beef

3/4 teaspoon ground black pepper

Vegetable oil

Salt, to taste

1/2 cup crumbled Stilton or Gorgonzola blue cheese

4 seeded hamburger buns

To prepare the french fried onions, in a medium saucepan combine the vinegar, sugar and bay leaves. Bring to a boil and then simmer for 5 minutes.

Meanwhile, in second medium saucepan, bring the water to a boil. Add the onions and blanch for 1 minute. Transfer to a colander to drain, then add the onions to the vinegar mixture and simmer for 1 minute.

Remove from heat and let cool in the pickling liquid for at least 15 minutes.

Meanwhile, in a medium bowl, whisk together the Wondra flour, dry mustard and salt.

In a 12-inch skillet, heat the oil over medium-high.

In small batches, shake the onions to remove excess liquid and dredge them through the flour mixture so they are completely coated. Fry the onions in the hot oil, turning them once, until they are golden brown, about 2 minutes per side. Adjust the heat as necessary to keep the onions from burning. Transfer to paper towels to drain.

To prepare the burgers, heat a gas grill to medium-high or prepare a charcoal fire.

In a large bowl, gently but thoroughly mix the ground beef and pepper. Shape into 4 patties, each about 3/4 inch thick.

To oil the grill grates, coat a folded paper towel with oil, hold it with tongs and rub it over the grates.

Grill the burgers, with the grill covered, until well browned on the underside, 4 to 5 minutes. With a metal spatula, carefully flip the burgers. Grill for another 3 minutes,

Top each burger with blue cheese crumbles. Grill 2 to 3 minutes more, or until the burger registers 160 F at the thickest part.

Meanwhile, toast the buns at the edge of the grill. Season the burgers with salt, top with the onions and serve the on the toasted buns.