- 3 Tbsp olive oil, plus more as needed
- 2 Lb yellow onions, sliced
- Salt (2 tsp Diamond Crystal Kosher / 1.5 tsp Morton’s Kosher / 1 tsp table)
- 3 tsp balsamic vinegar *
* Please, for the love of food, use a good, aged vinegar. This stuff is nothing like the watery salad-dressing balsamic vinegar you get. NOTHING. It’s a slightly sweet, near-syrup drizzle of heaven. You want something from Modena, Italy, and aged at least 14 years. Seven and nine year vinegar is too watery, and older vinegars are too expensive (at least for us…if you can swing it, go for it!). We use Mussini Riserva di Famiglia, which you can find on Amazon.com.
For the Walnuts:
- 3/4 Cup Walnuts or Pecans
- 3tsp Balsamic Vinegar
For the Sandwiches:
- Good bread, sliced 1/2 inch thick (we use Wegmans Garlic round loaf)
- Unsalted Butter, softened
- Granny Smith Apple, sliced 1/6″ thick
- Good cheddar, sliced 1/8″ thick, plus any other complementary cheeses
To make caramelized onions:
- Set a large, heavy (not non-stick) skillet over medium heat. Add the oil, onions, and salt. Cook stirring occasionally until onions get somewhat brown, about 10 minutes.
- Turn down the heat to low and cook stirring occasionally until onions are medium brown, about 30 minutes, adding more oil if they stick too much.
- Add balsamic vinegar, and cook stirring occasionally until onions are dark nutty brown, about 15 minutes. Take off heat. You’ll have way more onions than you’ll need for grilled cheese, but that’s not such a bad problem to have.
To prepare the walnuts:
- Chop the walnuts – a rough cut is nice, but this is a personal preference
- Place them in a pan over medium-high heat and toast, stirring frequently to ensure that they don’t burn (do not use oil in this process – just walnuts in a pan!)
- Reduce heat to low and add the Balsalmic vinegar, tossing to coat all walnuts evenly. Leave on heat just long enough to cook off any vinegar liquid in the pan – it should be coating the walnuts but not watery.
- Remove from heat.
To assemble sandwiches:
- Have 2 pieces of bread ready for each sandwich and butter each piece on one side (be generous with butter — you only live once 🙂
- Turn on the broiler.
- Set an oven-proof skillet, that can hold all the sandwiches you are making in one layer, over medium heat.
- Place 1 piece of bread per sandwich in the skillet, buttered side down. Arrange caramelized onions on top of bread, sprinkle with nuts, top with 1 layer of apples and then cheese. The order actually matters. You want the cheese to be on top so that it melts quickly under the broiler and the nuts to be next to the onions so that they stick and don’t fall out. Cook the sandwiches until the bottom of the bread is golden brown.
- Pop the skillet under the broiler for 1-2 minutes, just until the cheese melts. Check every 20 seconds since broilers vary widely.
- Return the skillet to the stove top on medium heat. Top with the second piece of bread, placing it buttered side up. Flip the sandwiches, and cook until the bread is golden brown on the bottom, pressing lightly on the sandwiches with a spatula to “smush” the melted cheese down into the apples, nuts, and onions.
- Serve with a German Riesling. It’s a food/wine match made in heaven.