Heirloom Tomato BLT with Brown Butter Mayonnaise

An Heirloom Tomato BLT sandwich is the ultimate way to celebrate summer tomatoes, and don’t even think about skipping the brown butter mayonnaise, it’s mandatory.

Heirloom Tomato BLT

I’ve been dying to share these Heirloom Tomato BLT sandwiches with you for what seems like ever. This is something I came up with last summer when I was cooking for a bunch of guys in their twenties who were craving filling food that wasn’t too fancy. Dude Food, if you will.

Heirloom Tomato BLT

BLTs were on the menu one day for lunch and I knew I had to Le Petit Chef-ify them somehow- people don’t hire a private chef for plain, unimaginative sandwiches. So in addition to using plump, juicy heirloom tomatoes, flavorful sourdough bread, organic bacon (my go-to is Applegate Farms Organic Sunday Bacon) and the best farmer’s market lettuce money could buy (little gem was made for BLTs), I figured I should also doctor up the mayo situation, and brown butter was the obvious choice.

Heirloom Tomato BLT

I certainly didn’t invent this brown butter mayonnaise; the recipe for that is something I saw on Food 52 awhile back. This is mayo you are making from scratch, people, and it’s not as scary and intimidating as you might think, at all! But it’s just the thing to elevate these Heirloom Tomato BLT sandwiches into something spectacular and noteworthy.

Heirloom Tomato BLT

Side note- you would be well advised to serve any and all brown butter mayo that is not reserved for sandwich purposes as a dipping option for artichokes. Think about it- when it comes to artichokes, some people are butter people and some people are mayo people. This magical condiment appeals to everyone!

Heirloom Tomato BLT

Anyway back to these Heirloom Tomato BLT sammies-  I’ve been waiting since last year for heirloom tomatoes to come back into season so that I could share this recipe with you. For the recipe pictured I used gluten free bread and some leftover turkey bacon I had from a cooking job. I try not to eat much animal protein these days and will usually opt for plant-based options instead, but if I have leftover ingredients from a job I don’t let them go to waste. My point is that you can make this sandwich as indulgent as you want, or lighten it up a bit. Make it a BLTA and add avocado. But DO NOT skip the brown butter mayo. And the heirloom tomatoes, if they’re in season, are everything.

Heirloom Tomato BLT

In other news- I just picked up three 3 week old kittens from the shelter that we’re going to foster until they’re ready for adoption! They are SO SO cute and tiny- they’ve barely just opened their eyes! Right now they’re mewing at me incessantly (because they can’t meow yet- they mew), so it must be feeding time again. Make sure you’re following me on Instagram for lots of baby kitty action over the next several weeks…if you’re into that.

Heirloom Tomato BLT
5 from 4 votes

Heirloom Tomato BLT with Brown Butter Mayonnaise

An Heirloom Tomato BLT sandwich is the ultimate way to celebrate summer tomatoes, and don't even think about skipping the brown butter mayonnaise, it's mandatory.

Course Main Course
Cuisine American
Keyword blt sandwich recipe, vegetarian sandwich recipe
Prep Time 10 minutes
Cook Time 17 minutes
Total Time 27 minutes
Servings 1
Calories 690 kcal
Author Denisse



  • 12 tablespoons unsalted butter
  • 1 large egg yolk at room temperature
  • 2 teaspoons freshly squeezed lemon juice
  • 1 teaspoon cold water
  • ¼ teaspoon kosher salt plus more to taste


  • 2 slices bread gluten free or regular
  • 2 slices pork or turkey bacon halved
  • 2-3 thick slices heirloom tomato
  • 2 leaves Little Gem or romaine lettuce


  1.  In a small skillet or saucepan over medium heat, melt the butter completely; cook until it turns brown and smells nutty, about 4 to 6 minutes. Be sure to stir frequently, scraping up any bits from the bottom so they don't burn. Take the pan off the heat and transfer the brown butter to a glass measuring cup with a spout. Let cool to just above room temperature. Combine egg yolk, lemon juice, cold water, and salt in a medium mixing bowl. Whisk until well integrated and bright yellow, about 30 seconds. Whisking constantly, add about half of the brown butter to the yolk mixture, a few drops at a time. Do not add the brown butter too rapidly; or an emulsion will not form.

    Gradually add remaining brown butter in a very slow, thin stream, whisking constantly, until mayonnaise is thick and spreadable. The process should take around 6-8 minutes (this step can also be done in a food processor. Season to taste.

  2. Toast bread and spread one slice (or both slices) evenly with brown butter mayonnaise.
  3. Layer bacon, tomato and lettuce over a slice of bread and top with the other slice.

Recipe Notes

The mayo also makes for an amazing addition to any salad dressing 


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  1. pretty

    I do love Heirloom Tomatoes, so happy they are in season again, will have to give the brown butter mayonnaise a try, sounds interesting.


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