GRILLED PORTOBELLO BURGERS with ONION JAM and HORSERADISH CREAM

For the Caramelized Onions:
4 tablespoons extra-virgin olive oil
2 medium-large red onions, thinly sliced
Kosher salt and freshly ground pepper
1/2 cup red wine
1/4 cup honey
1/4 cup red wine vinegar

For the Mushrooms:
2 tablespoons balsamic vinegar
4 large Portobello mushrooms, stemmed
Lettuce leaves
Heirloom Tomato slices
4 Kaiser Rolls, split and toasted

Put the yogurt in a cheesecloth-lined strainer set over a bowl and refrigerate to drain and thicken, about 1 hour.  Discard the watery liquid and whisk the horseradish into the thickened yogurt.

Meanwhile, heat 2 tablespoons of the olive oil in a large skillet, over medium heat.  Add the onions and season with salt and pepper, to taste. Sauté over medium heat, stirring often, until the onions have caramelized about 20 to 25 minutes.  Add the red wine and deglaze.  Bring the wine to a simmer and cook until almost entirely reduced.  Add the honey and red wine vinegar and simmer gently until the onions get jam-like, about 15 minutes more.

Preheat the barbecue or stove-top grill pan to high.  Whisk the remaining 2 tablespoons of olive oil with the balsamic vinegar in a mixing bowl.  Brush the mushroom caps with the mixture, season with salt and pepper and grill the mushrooms, turning as needed, until tender, about 3 to 4 minutes per side.

Sandwich the grilled mushrooms between the toasted buns and top with onion jam, lettuce and the horseradish cream.

Serves 4