Makes 10 servings
4 pounds medium-size red onions
3/4 cup olive oil
salt and pepper
6 tablespoon butter
3 tablespoon sugar
6 tablespoon balsamic vinegar
1 tablespoon fresh parsley, chopped
Preheat oven to 500F. Line 2 large baking sheets with foil. Cut onions through root end into 3/4 inch thick wedges. Toss with oil. Arrange onions, cut side down, on baking sheets. Sprinkle with salt and pepper. Roast until onions are brown and tender, about 45 minutes.
Meanwhile, melt butter in heavy saucepan over medium-high heat. Add sugar and stir until dissolved. Remove from heat. Add vinegar and return to heat. Simmer until mixture thickens slightly, about two minutes. (Onions and glaze and can be made 1 day ahead. Cover separately and chill. Reheat onions about 15 minutes at 375F. Stir glaze over low heat to warm.)
Arrange onions on platter and drizzle glaze over. Sprinkle with parsley and serve.