- 1 tablespoon extra virgin olive oil (EVOO)
- 1 tablespoon butter
- 1 large onion, sliced
- Salt and freshly ground black pepper
- 1 tablespoon brown sugar
- A splash of water
- 1/4 cup spicy brown mustard
- 1 1/2 pounds ground sirloin
- 2 cloves garlic, grated
- 3 tablespoons Worcestershire sauce (eyeball it)
- A handful of fresh parsley, finely chopped
- 1/2 pound Cambazola blue cheese, thinly sliced
- 4 crusty rolls, split, lightly toasted
- 2 handfuls arugula leaves, coarsely chopped
Heat 1 tablespoon of EVOO and 1 tablespoon butter in a skillet over medium heat. Add the onion, season with salt and pepper and cook until caramelized and sweet, about 20 minutes. Stir the brown sugar and the water into the onion, then add the mustard, combine and turn off the heat.
Combine the meat with the garlic, Worcestershire sauce, parsley, salt and pepper. Form four patties that are thinner at the center and thicker at the edges for even cooking – the burgers will bulge as they cook, so doing this will give the cooked burgers an even thickness.
Cook the patties on a grill pan over medium-high heat for 8 minutes, turning once for medium doneness, 1-2 minutes less for rare patties and 1-2 minutes more for burgers that are medium-well done. In the last minute of cooking time, top the burgers with a few slices of the Cambozola blue cheese.
Place the burgers on the bun bottoms. Top with some arugula and mustard-glazed onions, then set the bun tops in place.