Heirloom Tomato Panini…Relax and Simplify

The temptation to sneak in a few slices of thick-cut bacon on these Heirloom Tomato Panini was so strong. I so badly wanted to just chop a little fresh basil from my garden and mix it in with the homemade mayo. Just one little piece of fresh mozzarella? But everything I’ve been hearing about the good old-fashioned tomato sandwich is that its beauty is in its simplicity. So I stayed strong.

Big slices of summer heirloom tomatoes, homemade olive oil mayo and sourdough bread…seasoned with a little flaked sea salt and pepper…that’s it.

And it honestly is all you need. I couldn’t have imagined how such simple ingredients – and so few of of them – could combine into such blissful sweet, salty, briny bites. You know me, I’m a meat and cheese kind of girl. That a tomato sandwich stopped me in my tracks is kind of huge.

I know that a lot of people swear by regular store-bought mayo for this type of sandwich, but I just couldn’t resist the opportunity to try out the perfectly inexact mayonnaise-making method that Amy Finley described in her food memoir, How to Eat a Small Country. After countless failed attempts at following mayonnaise recipes to the letter, Amy finally threw caution to the wind and mirrored the actions of a confident, relaxed friend who used no measurements or special techniques. Voilà – perfect mayonnaise! I gave it a try and was just amazed.

Relax and simplify…I could get used to this.


Heirloom Tomato Panini with Homemade Olive Oil Mayo

The Olive Oil Mayonnaise “recipe” is adapted from How to Eat a Small Country, by Amy Finley – an inexact but highly reliable method that Amy learned from observing a confident, relaxed friend in France.

Prep time: 10 min | Cook time: 2 min | Total time: 12 min


Olive Oil Mayonnaise

  • 1 egg yolk
  • 1 slosh white wine vinegar
  • 1 sprinkle salt
  • A few pinches sugar
  • A spoon Dijon mustard
  • 1 cup extra-virgin olive oil (I used a measurement here, for those who may be unsure of how much oil is “enough”)


  • 8 slices sourdough bread
  • 2 heirloom tomatoes, sliced thickly
  • 1/4 cup Olive Oil Mayonnaise (or store-bought mayonnaise)
  • Sea salt and freshly cracked black pepper


For the Olive Oil Mayonnaise:

  1. Add the egg yolk, white wine vinegar, salt, sugar and Dijon mustard to a small bowl. Roll up a dish towel and wrap it around the base of bowl to keep it stable. While pouring olive oil steadily into the bowl with one hand, whisk briskly with the other until the mayonnaise is emulsified, light and fluffy.
  2. Season with more salt or sugar as needed (It may be on the bitter side, due to the olive oil, but trust me it’s amazing with the tomatoes. If it’s too bitter for your taste, add a little sugar). Refrigerate any unused mayonnaise in a covered bowl – it’s best to use it within 2-3 days.

For the Panini:

  1. Preheat the panini grill to High.
  2. For each sandwich: Spread a few teaspoons of mayonnaise on two slices of bread. Add tomato slices to one slice of bread (enough to cover). Season the tomatoes with salt and pepper. Close the sandwich with the other slice of bread, mayonnaise side down.
  3. Place the sandwich on the grill and close the lid just so that the grates are touching the top of the sandwich without pressing it. Grill for 1-2 minutes just until the bread is toasted. 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 sounds great! I love the idea of olive oil mayo!

    Posted 7.25.11 Reply
  2. Yum! Your sandwich looks awesome! I have always wanted to try making my own mayonnaise. I gotta give it a try!

    Posted 7.25.11 Reply
  3. Simple and delicious too I bet!

    Posted 7.25.11 Reply
  4. So simple, but so lovely! I haven’t made mayo in a while – perhaps it’s time.

    Posted 7.25.11 Reply
  5. Angela FRS wrote:

    That looks *fabulous* in all its beautiful simplicity.

    Posted 7.25.11 Reply
  6. Emily wrote:

    This is one good looking sandwich!

    I would love to make my own mayonnaise. I bet it tastes amazing!

    Posted 7.25.11 Reply
  7. This sandwich looks simple and perfect! Love the homamde mayo.

    Posted 7.26.11 Reply
  8. This is perfect summer sandwich! Yum@

    Posted 7.26.11 Reply
  9. Mayo and tomatoes are a match made in heaven. I love this post and the fact that you stood strong in the face of preserving the sophistication of these simple ingredients. Not to mention such a beautiful photograph. Love it Kathy:)

    Posted 7.26.11 Reply
  10. Aggie wrote:

    that mayo sounds really good! I would have had trouble sticking to the simplicity of this too…but simple is so good isn’t it?? what a beautiful sandwich. Yum.

    Posted 7.26.11 Reply
  11. Deb wrote:

    This sounds great! I recently got some Himalayan pink salt and organic peppercorns from Sustainable Sourcing and I’ll have to try them out in this recipe. Thanks for sharing!

    Posted 7.26.11 Reply
  12. zainab wrote:

    this is so lovely…and really quick too!!!
    great blog!

    Posted 7.29.11 Reply
  13. Louise wrote:

    Hi Kathy!!!

    I just couldn’t let another day go by without wishing you a Happy National Panini Month!!! Your Heirloom Tomato Panini looks heavenly. I’m still waiting for my heirlooms. Simply delectable.

    Thanks for sharing…

    Posted 8.2.11 Reply
    • Kathy wrote:

      Thank you, Louise! 🙂

      Posted 8.2.11 Reply
  14. Mindy wrote:

    I totally need to try this next time I get heirlooms from the CSA! I used to make mayo (without a recipe) when I lived in Spain long ago, but got out of the habit. It’s soooooo much better fresh!

    Posted 8.2.11 Reply
  15. Love the idea of keeping it simple with just the tomato and the homemade mayo. I’d have been tempted to add bacon too though 🙂 Looking forward to having a couple of dinners with you this week!

    Posted 8.3.11 Reply
  16. I would have had a hard time not adding the bacon too, but those are gorgeous tomatoes. I’m sure it was a treat.

    Posted 8.4.11 Reply
  17. Ashley wrote:

    This looks amazing!! I love fresh tomatoes. What a perfect lunch!

    Posted 8.19.11 Reply