Beef Burgers with Blue Cheese and Caramelized Onions

Ingredients

• 4 brioche or challah rolls, split
• 2 Tbs. unsalted butter
• Vegetable oil, for the grill
• 4 oz. blue cheese, crumbled (about 1 cup)
• 2 medium yellow onions, chopped (about 2 cups)
• 1 Tbs. chopped fresh tarragon
• 1-½ lb. ground beef (preferably 85% lean)
• + 2 more ingredients
• • 1 Tbs. Dijon mustard
  • 1 Tbs. Worcestershire sauce (preferably Lea & Perrins)

Prepare a medium-high gas or charcoal grill fire. Melt the butter in a 12-inch skillet over medium-low heat. Add the onions and cook, stirring often, until golden and soft, about 20 minutes; reduce the heat to low if the onions begin to brown too quickly. Meanwhile, in a large bowl, thoroughly ...

View full recipe at Fine Cooking