Grilled Gruyere Panini with Pickled Sweet Onions

For those who are counting, today marks the third occasion on which I’ve posted about Gruyère and onion panini (fourth, if you count the French Dip panini, which also contains roast beef). I’ve made these panini with caramelized onions and with marinated onions…now I’m pickling the onions. Seriously, the combination never gets old.

There’s a Pickling Party happening today (stemming from the enthusiasm over last month’s Pie Party), with more than 300 food bloggers and other cooking enthusiasts making and sharing pickled things. What’s great about the pickled sweet onions I made for the occasion is that you don’t have to know how to can (because I don’t). All you have to do is combine a few simple ingredients together and wait.

There are few foods that will brighten up the flavor of a sandwich better than a pickle. They bring that big punch of acidity and, in the case of the onions I’m sharing today, a good dose of sweetness and spice. I let some sweet Walla Walla onions bathe in apple cider vinegar, brown sugar, salt and allspice until they were ready to get some mouths watering. Grab yourself a little bowl of fresh tomato soup to go along with them and get ready for a treat.

Grilled Gruyere with Pickled Sweet Onions

Grilled Gruyère Panini with Pickled Sweet Onions

Prep time: 1 hour 10 minutes | Cook time: 12 minutes | Total time: 1 hour 22 minutes

Yield: 4 panini


  • 1 medium sweet onion such as Vidalia, Walla Walla or Maui, halved and thinly sliced
  • 1/4 cup cider vinegar
  • 1 teaspoon packed brown sugar
  • 1/2 teaspoon kosher salt
  • 1/4 teaspoon allspice
  • 4 ciabatta rolls, or 1 large ciabatta loaf cut crosswise into 4 pieces
  • 8 ounces Gruyère cheese, shredded


To make the pickled sweet onions:

  1. Bring a small pot of water to boil over high heat. Add the onions and blanch them for about 15 seconds. Drain well and set aside.
  2. In a large nonreactive bowl , combine the vinegar, brown sugar, salt and allspice. Stir until the sugar is dissolved. Add the blanched onion slices and stir to coat thoroughly. Cover and refrigerate at least 1 hour before serving.

To make the panini:

  1. Preheat the panini grill to medium high heat.
  2. Halve each of the ciabatta rolls lengthwise. On each the bottom halves, add a few tablespoons of cheese. Top with onions (as much as you’d like, you can always refrigerate any extra onions) and the rest of the cheese. Close the panini with the top halves of bread.
  3. In batches, grill the panini for 4 to 6 minutes until the cheese is melted and the bread is toasted. Slice in half diagonally and serve immediately.



KathyPanini Happy, online since 2008, is more than just a sandwich blog. Here, you'll find hundreds of my original panini recipes, my guide to choosing a panini press and a whole lot of other creative uses for the panini press.
~ Kathy Strahs
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  1. This looks great! Hope you’re well!

    Posted 8.10.11 Reply
  2. Maria wrote:

    I bet the pickled onions add great flavor to this panini!

    Posted 8.10.11 Reply
  3. This looks really good! I’m a little nervous about the pickled sweet onions, not going to lie…but I’d be willing to try it 🙂

    Posted 8.10.11 Reply
  4. Colleen wrote:

    I really like pickled anything. Yum!

    Posted 8.10.11 Reply
  5. Aggie wrote:

    I absolutely love pickled onions. I have to start making them at home. I had them on an egg sandwich once and it rocked. This looks delicious!!

    Posted 8.10.11 Reply
  6. Cyndi wrote:

    This was a big hit with my husband and me. I made them for lunch and he kept saying how good it was and that I could make this again. I love Gruyère cheese anyway and the onions and cheese were a super combo.

    Posted 8.15.11 Reply
    • Kathy wrote:

      That’s great to hear, Cyndi – I’m so glad you guys liked them!

      Posted 8.15.11 Reply
  7. Eliana wrote:

    Gruyere is one of my absolute favorite cheeses! So this panini looks perfect to me.

    Posted 8.23.11 Reply