Ingredients

2 large onions, sliced into 1/4-inch rings

2 sprigs rosemary

2 tablespoons olive oil

2 tablespoons balsamic vinegar

Salt and pepper

Preparation

In a bowl, toss onions, rosemary, olive oil, and balsamic vinegar; season with salt and pepper.

Transfer onions to hot wok, reserving bowl and marinade; cook onions, tossing frequently, until golden and caramelized, 20 to 40 minutes.

Return onions to bowl; toss with reserved marinade.