Emmentaler on Rye with Sweet & Sour Onions
Onions:
- 1 tablespoon olive oil
- 1 tablespoon unsalted butter
- 1 large red onion, halved and thinly sliced (about 2 cups)
- 2 teaspoons brown sugar, light or dark
- ¼ teaspoon table salt, plus more to taste
- 1 tablespoon balsamic vinegar
- Freshly ground black pepper
- Four ½-inch-thick slices rye bread
- 2 tablespoons (30 grams) butter, salted or unsalted, softened
- ¾ cup (about 3 ounces or 85 grams) grated Emmentaler or another Swiss cheese
Instructions:
Those onions are cooked slow and low until sweet and tart and resonating with immense flavor.
- Heat the olive oil and 1 tablespoon butter in a large skillet over medium-high heat. Add the onion, and sauté for 5 minutes. Add the brown sugar and salt, lower the heat to medium-low, and cook another 10 minutes, stirring occasionally. Add the vinegar, and scrape any stuck onion bits from the bottom of pan with a spoon. Simmer for 1 to 2 minutes, until the onion mixture thickens, and season to taste with black pepper. Cool to lukewarm, or store in an airtight container in the refrigerator until needed, up to 5 days. You should have just shy of ½ cup of cooked onions.
- Generously butter one side of each slice of bread; these will be the outsides of your sandwiches. Arrange one slice, buttered side down, on a plate. Spread thickly with jammy onions (about 2 tablespoons per sandwich; you’ll have extra). Sprinkle with half the grated cheese. Arrange a second slice of bread on top of the cheese, buttered side facing up. Repeat with the remaining slices to make a second sandwich.
- Heat a heavy 12-inch skillet over medium-low heat. Once it’s hot, arrange your sandwiches in the pan, and cook them until crisp and deep golden brown, about 5 minutes per side. If you are making a larger batch and want to keep them warm and melty, arrange them in a single layer on a baking sheet in a 200-degree oven. When ready to eat, slice the sandwiches in half. Don’t expect leftovers.